diff --git a/Cargo.toml b/Cargo.toml
index 05416be9b..569347ec1 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -76,6 +76,7 @@ actix-base = ["v2", "paperclip-macros/actix"]
 swagger-ui = ["paperclip-actix/swagger-ui"]
 rapidoc = ["paperclip-actix/rapidoc"]
 path-in-definition = ["paperclip-macros/path-in-definition"]
+preserve_order = ["paperclip-core/preserve_order"]
 
 # OpenAPI support (v2 and codegen)
 cli = ["env_logger", "structopt", "git2", "v2", "codegen"]
diff --git a/core/Cargo.toml b/core/Cargo.toml
index 69885e91e..23cac59b4 100644
--- a/core/Cargo.toml
+++ b/core/Cargo.toml
@@ -18,6 +18,7 @@ actix-session = { version = "0", optional = true }
 actix-identity = { version = "0", optional = true }
 actix-files = { version = "0", optional = true }
 chrono = { version = "0.4", optional = true }
+indexmap = { version = "2", optional = true }
 jiff = { version = "0.1.5", optional = true }
 heck = { version = "0.4", optional = true }
 once_cell = "1.4"
@@ -57,6 +58,7 @@ nightly = ["paperclip-macros/nightly"]
 v2 = ["paperclip-macros/v2"]
 v3 = ["v2", "openapiv3"]
 codegen = ["v2", "heck", "log"]
+preserve_order = ["dep:indexmap", "indexmap/serde", "serde_json/preserve_order"]
 uuid = ["uuid0"]
 uuid0 = ["uuid0_dep"]
 uuid1 = ["uuid1_dep"]
diff --git a/core/src/v2/mod.rs b/core/src/v2/mod.rs
index 89a95a91f..a8d2e0a29 100644
--- a/core/src/v2/mod.rs
+++ b/core/src/v2/mod.rs
@@ -29,6 +29,11 @@ use self::resolver::Resolver;
 #[cfg(feature = "codegen")]
 use crate::error::ValidationError;
 
+#[cfg(feature = "preserve_order")]
+pub type PropertiesMap<K, V> = indexmap::IndexMap<K, V>;
+#[cfg(not(feature = "preserve_order"))]
+pub type PropertiesMap<K, V> = std::collections::BTreeMap<K, V>;
+
 #[cfg(feature = "codegen")]
 impl<S: Schema + Default> ResolvableApi<S> {
     /// Consumes this API schema, resolves the references and returns
diff --git a/core/src/v2/schema.rs b/core/src/v2/schema.rs
index b882f3e49..f8d822aab 100644
--- a/core/src/v2/schema.rs
+++ b/core/src/v2/schema.rs
@@ -1,8 +1,11 @@
 //! Traits used for code and spec generation.
 
-use super::models::{
-    DataType, DataTypeFormat, DefaultOperationRaw, DefaultSchemaRaw, Either, Resolvable,
-    SecurityScheme,
+use super::{
+    models::{
+        DataType, DataTypeFormat, DefaultOperationRaw, DefaultSchemaRaw, Either, Resolvable,
+        SecurityScheme,
+    },
+    PropertiesMap,
 };
 
 use std::collections::{BTreeMap, BTreeSet};
@@ -39,10 +42,10 @@ pub trait Schema: Sized {
     fn additional_properties_mut(&mut self) -> Option<&mut Either<bool, Resolvable<Self>>>;
 
     /// Map of names and schema for properties, if it's an object (`properties` field)
-    fn properties(&self) -> Option<&BTreeMap<String, Resolvable<Self>>>;
+    fn properties(&self) -> Option<&PropertiesMap<String, Resolvable<Self>>>;
 
     /// Mutable access to `properties` field.
-    fn properties_mut(&mut self) -> Option<&mut BTreeMap<String, Resolvable<Self>>>;
+    fn properties_mut(&mut self) -> Option<&mut PropertiesMap<String, Resolvable<Self>>>;
 
     /// Returns the required properties (if any) for this object.
     fn required_properties(&self) -> Option<&BTreeSet<String>>;
diff --git a/core/src/v3/schema.rs b/core/src/v3/schema.rs
index 1f2bd0d21..0b8233d31 100644
--- a/core/src/v3/schema.rs
+++ b/core/src/v3/schema.rs
@@ -1,4 +1,4 @@
-use crate::v2::models::Either;
+use crate::v2::{models::Either, PropertiesMap};
 
 use super::{invalid_referenceor, v2};
 use std::ops::Deref;
@@ -65,7 +65,7 @@ fn v2_data_type_to_v3(
     format: &Option<v2::DataTypeFormat>,
     enum_: &[serde_json::Value],
     items: &Option<Box<v2::DefaultSchemaRaw>>,
-    properties: &std::collections::BTreeMap<String, Box<v2::DefaultSchemaRaw>>,
+    properties: &PropertiesMap<String, Box<v2::DefaultSchemaRaw>>,
     extra_properties: &Option<Either<bool, Box<v2::DefaultSchemaRaw>>>,
     required: &std::collections::BTreeSet<String>,
 ) -> openapiv3::SchemaKind {
diff --git a/macros/src/core.rs b/macros/src/core.rs
index 3870c0c29..9f9aeef0c 100644
--- a/macros/src/core.rs
+++ b/macros/src/core.rs
@@ -148,7 +148,7 @@ pub fn emit_v2_schema_struct(input: TokenStream) -> TokenStream {
             }
 
             #[inline]
-            fn properties(&self) -> Option<&std::collections::BTreeMap<String, paperclip::v2::models::Resolvable<Self>>> {
+            fn properties(&self) -> Option<&paperclip::v2::PropertiesMap<String, paperclip::v2::models::Resolvable<Self>>> {
                 if self.properties.is_empty() {
                     None
                 } else {
@@ -157,7 +157,7 @@ pub fn emit_v2_schema_struct(input: TokenStream) -> TokenStream {
             }
 
             #[inline]
-            fn properties_mut(&mut self) -> Option<&mut std::collections::BTreeMap<String, paperclip::v2::models::Resolvable<Self>>> {
+            fn properties_mut(&mut self) -> Option<&mut paperclip::v2::PropertiesMap<String, paperclip::v2::models::Resolvable<Self>>> {
                 if self.properties.is_empty() {
                     None
                 } else {
@@ -298,8 +298,8 @@ fn schema_fields(name: &Ident, is_ref: bool) -> proc_macro2::TokenStream {
     ));
 
     gen.extend(quote!(
-        #[serde(default, skip_serializing_if = "std::collections::BTreeMap::is_empty")]
-        pub properties: std::collections::BTreeMap<String,
+        #[serde(default, skip_serializing_if = "paperclip::v2::PropertiesMap::is_empty")]
+        pub properties: paperclip::v2::PropertiesMap<String,
     ));
     add_self(&mut gen);
     gen.extend(quote!(>,));
diff --git a/src/v2/codegen/emitter.rs b/src/v2/codegen/emitter.rs
index f30763d99..8a5de8252 100644
--- a/src/v2/codegen/emitter.rs
+++ b/src/v2/codegen/emitter.rs
@@ -549,7 +549,7 @@ where
         self.emit_struct(def, ctx)
     }
 
-    /// Checks if the given definition is a simple map and returns the corresponding `BTreeMap`.
+    /// Checks if the given definition is a simple map and returns the corresponding `PropertiesMap`.
     fn try_emit_map(
         &self,
         def: &E::Definition,
@@ -565,7 +565,7 @@ where
                 let ty = self
                     .build_def(&schema, ctx.clone().define(false))?
                     .known_type();
-                let map = format!("std::collections::BTreeMap<String, {}>", ty);
+                let map = format!("paperclip::v2::PropertiesMap<String, {}>", ty);
                 Ok(EmittedUnit::Known(map))
             }
             _ => Ok(EmittedUnit::None),
@@ -673,7 +673,7 @@ where
             if let Some(Either::Left(true)) = def.additional_properties() {
                 obj.fields_mut().push(ObjectField {
                     name: EXTRA_PROPS_FIELD.into(),
-                    ty_path: "std::collections::BTreeMap<String, Any>".into(),
+                    ty_path: "paperclip::v2::PropertiesMap<String, Any>".into(),
                     description: None,
                     is_required: false,
                     needs_any: true,
diff --git a/src/v2/codegen/impls.rs b/src/v2/codegen/impls.rs
index 4ce40cd34..709930770 100644
--- a/src/v2/codegen/impls.rs
+++ b/src/v2/codegen/impls.rs
@@ -470,7 +470,7 @@ where
     /// Builds the method parameter type using the actual field type.
     ///
     /// For example, if a field is `Vec<T>`, then we replace it (in builder method)
-    /// with `impl Iterator<Item=Into<T>>`, and if we had `BTreeMap<String, T>`,
+    /// with `impl Iterator<Item=Into<T>>`, and if we had `PropertiesMap<String, T>`,
     /// then we replace it with `impl Iterator<Item = (String, T)>` and
     /// we do this... recursively.
     // FIXME: Investigate if there's a better way.
@@ -489,7 +489,7 @@ where
                 f.write_str("impl Iterator<Item = ")?;
                 self.write_builder_ty(&ty[i + 1..ty.len() - 1], req, needs_any, f)?;
                 f.write_str(">")?;
-            } else if ty[..i].ends_with("std::collections::BTreeMap") {
+            } else if ty[..i].ends_with("paperclip::v2::PropertiesMap") {
                 f.write_str("impl Iterator<Item = (String, ")?;
                 self.write_builder_ty(&ty[i + 9..ty.len() - 1], req, needs_any, f)?;
                 f.write_str(")>")?;
@@ -546,10 +546,10 @@ where
                 f.write_str("value.map(|value| ")?;
                 Self::write_value_map(&ty[i + 1..ty.len() - 1], f)?;
                 f.write_str(").collect::<Vec<_>>()")?;
-            } else if ty[..i].ends_with("std::collections::BTreeMap") {
+            } else if ty[..i].ends_with("paperclip::v2::PropertiesMap") {
                 f.write_str("value.map(|(key, value)| (key, ")?;
                 Self::write_value_map(&ty[i + 9..ty.len() - 1], f)?;
-                f.write_str(")).collect::<std::collections::BTreeMap<_, _>>()")?;
+                f.write_str(")).collect::<paperclip::v2::PropertiesMap<_, _>>()")?;
             }
         } else {
             f.write_str("value")?;
diff --git a/src/v2/codegen/object.rs b/src/v2/codegen/object.rs
index 3ddc7aa35..a6bfb67cb 100644
--- a/src/v2/codegen/object.rs
+++ b/src/v2/codegen/object.rs
@@ -222,8 +222,8 @@ pub struct ObjectField {
     /// Required fields of the "deepest" child type in the given definition.
     ///
     /// Now, what do I mean by "deepest"? For example, if we had `Vec<Vec<Vec<T>>>`
-    /// or `Vec<BTreeMap<String, Vec<BTreeMap<String, T>>>>`, then "deepest" child
-    /// type is T (as long as it's not a `Vec` or `BTreeMap`).
+    /// or `Vec<PropertiesMap<String, Vec<PropertiesMap<String, T>>>>`, then "deepest" child
+    /// type is T (as long as it's not a `Vec` or `PropertiesMap`).
     ///
     /// To understand why we're doing this, see `ApiObjectBuilderImpl::write_builder_ty`
     /// and `ApiObjectBuilderImpl::write_value_map` functions.
@@ -315,7 +315,7 @@ impl ApiObject {
             if ty[..i].ends_with("Vec") {
                 f.write_str(&ty[..=i])?;
                 Self::write_field_with_any(&ty[i + 1..ty.len() - 1], f)?;
-            } else if ty[..i].ends_with("std::collections::BTreeMap") {
+            } else if ty[..i].ends_with("paperclip::v2::PropertiesMap") {
                 f.write_str(&ty[..i + 9])?;
                 Self::write_field_with_any(&ty[i + 9..ty.len() - 1], f)?;
             } else {
diff --git a/src/v2/mod.rs b/src/v2/mod.rs
index 28a14e8c1..9b31212a3 100644
--- a/src/v2/mod.rs
+++ b/src/v2/mod.rs
@@ -102,7 +102,7 @@ pub use paperclip_core::{
     v2::{
         models::{self, DefaultSchema, ResolvableApi},
         schema::{self, Schema},
-        serde_json,
+        serde_json, PropertiesMap,
     },
 };
 
diff --git a/tests/snapshots/test_codegen__tests__test_k8s__io__k8s__api__certificates__v1beta1__certificate_signing_request_spec.rs.snap b/tests/snapshots/test_codegen__tests__test_k8s__io__k8s__api__certificates__v1beta1__certificate_signing_request_spec.rs.snap
index 13bfbfdb3..096b206e9 100644
--- a/tests/snapshots/test_codegen__tests__test_k8s__io__k8s__api__certificates__v1beta1__certificate_signing_request_spec.rs.snap
+++ b/tests/snapshots/test_codegen__tests__test_k8s__io__k8s__api__certificates__v1beta1__certificate_signing_request_spec.rs.snap
@@ -7,7 +7,7 @@ expression: data
 #[derive(Debug, Default, Clone, Serialize, Deserialize)]
 pub struct CertificateSigningRequestSpec {
     /// Extra information about the requesting user. See user.Info interface for details.
-    pub extra: Option<std::collections::BTreeMap<String, Vec<String>>>,
+    pub extra: Option<paperclip::v2::PropertiesMap<String, Vec<String>>>,
     /// Group information about the requesting user. See user.Info interface for details.
     pub groups: Option<Vec<String>>,
     /// Base64-encoded PKCS#10 CSR data
@@ -49,7 +49,7 @@ impl<Request> CertificateSigningRequestSpecBuilder<Request> {
     /// Extra information about the requesting user. See user.Info interface for details.
     #[inline]
     pub fn extra(mut self, value: impl Iterator<Item = (String, impl Iterator<Item = impl Into<String>>)>) -> Self {
-        self.body.extra = Some(value.map(|(key, value)| (key, value.map(|value| value.into()).collect::<Vec<_>>().into())).collect::<std::collections::BTreeMap<_, _>>().into());
+        self.body.extra = Some(value.map(|(key, value)| (key, value.map(|value| value.into()).collect::<Vec<_>>().into())).collect::<paperclip::v2::PropertiesMap<_, _>>().into());
         self
     }
 
diff --git a/tests/snapshots/test_codegen__tests__test_k8s__io__k8s__api__core__v1__config_map.rs.snap b/tests/snapshots/test_codegen__tests__test_k8s__io__k8s__api__core__v1__config_map.rs.snap
index b461142c7..cbd5f339f 100644
--- a/tests/snapshots/test_codegen__tests__test_k8s__io__k8s__api__core__v1__config_map.rs.snap
+++ b/tests/snapshots/test_codegen__tests__test_k8s__io__k8s__api__core__v1__config_map.rs.snap
@@ -11,9 +11,9 @@ pub struct ConfigMap {
     pub api_version: Option<String>,
     /// BinaryData contains the binary data. Each key must consist of alphanumeric characters, '-', '_' or '.'. BinaryData can contain byte sequences that are not in the UTF-8 range. The keys stored in BinaryData must not overlap with the ones in the Data field, this is enforced during validation process. Using this field will require 1.10+ apiserver and kubelet.
     #[serde(rename = "binaryData")]
-    pub binary_data: Option<std::collections::BTreeMap<String, String>>,
+    pub binary_data: Option<paperclip::v2::PropertiesMap<String, String>>,
     /// Data contains the configuration data. Each key must consist of alphanumeric characters, '-', '_' or '.'. Values with non-UTF-8 byte sequences must use the BinaryData field. The keys stored in Data must not overlap with the keys in the BinaryData field, this is enforced during validation process.
-    pub data: Option<std::collections::BTreeMap<String, String>>,
+    pub data: Option<paperclip::v2::PropertiesMap<String, String>>,
     /// Kind is a string value representing the REST resource this object represents. Servers may infer this from the endpoint the client submits requests to. Cannot be updated. In CamelCase. More info: https://git.k8s.io/community/contributors/devel/api-conventions.md#types-kinds
     pub kind: Option<String>,
     /// Standard object's metadata. More info: https://git.k8s.io/community/contributors/devel/api-conventions.md#metadata
@@ -94,14 +94,14 @@ impl ConfigMapBuilder {
     /// BinaryData contains the binary data. Each key must consist of alphanumeric characters, '-', '_' or '.'. BinaryData can contain byte sequences that are not in the UTF-8 range. The keys stored in BinaryData must not overlap with the ones in the Data field, this is enforced during validation process. Using this field will require 1.10+ apiserver and kubelet.
     #[inline]
     pub fn binary_data(mut self, value: impl Iterator<Item = (String, impl Into<String>)>) -> Self {
-        self.body.binary_data = Some(value.map(|(key, value)| (key, value.into())).collect::<std::collections::BTreeMap<_, _>>().into());
+        self.body.binary_data = Some(value.map(|(key, value)| (key, value.into())).collect::<paperclip::v2::PropertiesMap<_, _>>().into());
         self
     }
 
     /// Data contains the configuration data. Each key must consist of alphanumeric characters, '-', '_' or '.'. Values with non-UTF-8 byte sequences must use the BinaryData field. The keys stored in Data must not overlap with the keys in the BinaryData field, this is enforced during validation process.
     #[inline]
     pub fn data(mut self, value: impl Iterator<Item = (String, impl Into<String>)>) -> Self {
-        self.body.data = Some(value.map(|(key, value)| (key, value.into())).collect::<std::collections::BTreeMap<_, _>>().into());
+        self.body.data = Some(value.map(|(key, value)| (key, value.into())).collect::<paperclip::v2::PropertiesMap<_, _>>().into());
         self
     }
 
@@ -176,14 +176,14 @@ impl<Namespace> ConfigMapPostBuilder<Namespace> {
     /// BinaryData contains the binary data. Each key must consist of alphanumeric characters, '-', '_' or '.'. BinaryData can contain byte sequences that are not in the UTF-8 range. The keys stored in BinaryData must not overlap with the ones in the Data field, this is enforced during validation process. Using this field will require 1.10+ apiserver and kubelet.
     #[inline]
     pub fn binary_data(mut self, value: impl Iterator<Item = (String, impl Into<String>)>) -> Self {
-        self.inner.body.binary_data = Some(value.map(|(key, value)| (key, value.into())).collect::<std::collections::BTreeMap<_, _>>().into());
+        self.inner.body.binary_data = Some(value.map(|(key, value)| (key, value.into())).collect::<paperclip::v2::PropertiesMap<_, _>>().into());
         self
     }
 
     /// Data contains the configuration data. Each key must consist of alphanumeric characters, '-', '_' or '.'. Values with non-UTF-8 byte sequences must use the BinaryData field. The keys stored in Data must not overlap with the keys in the BinaryData field, this is enforced during validation process.
     #[inline]
     pub fn data(mut self, value: impl Iterator<Item = (String, impl Into<String>)>) -> Self {
-        self.inner.body.data = Some(value.map(|(key, value)| (key, value.into())).collect::<std::collections::BTreeMap<_, _>>().into());
+        self.inner.body.data = Some(value.map(|(key, value)| (key, value.into())).collect::<paperclip::v2::PropertiesMap<_, _>>().into());
         self
     }
 
@@ -363,14 +363,14 @@ impl<Name, Namespace> ConfigMapPutBuilder1<Name, Namespace> {
     /// BinaryData contains the binary data. Each key must consist of alphanumeric characters, '-', '_' or '.'. BinaryData can contain byte sequences that are not in the UTF-8 range. The keys stored in BinaryData must not overlap with the ones in the Data field, this is enforced during validation process. Using this field will require 1.10+ apiserver and kubelet.
     #[inline]
     pub fn binary_data(mut self, value: impl Iterator<Item = (String, impl Into<String>)>) -> Self {
-        self.inner.body.binary_data = Some(value.map(|(key, value)| (key, value.into())).collect::<std::collections::BTreeMap<_, _>>().into());
+        self.inner.body.binary_data = Some(value.map(|(key, value)| (key, value.into())).collect::<paperclip::v2::PropertiesMap<_, _>>().into());
         self
     }
 
     /// Data contains the configuration data. Each key must consist of alphanumeric characters, '-', '_' or '.'. Values with non-UTF-8 byte sequences must use the BinaryData field. The keys stored in Data must not overlap with the keys in the BinaryData field, this is enforced during validation process.
     #[inline]
     pub fn data(mut self, value: impl Iterator<Item = (String, impl Into<String>)>) -> Self {
-        self.inner.body.data = Some(value.map(|(key, value)| (key, value.into())).collect::<std::collections::BTreeMap<_, _>>().into());
+        self.inner.body.data = Some(value.map(|(key, value)| (key, value.into())).collect::<paperclip::v2::PropertiesMap<_, _>>().into());
         self
     }
 
diff --git a/tests/snapshots/test_codegen__tests__test_k8s__io__k8s__apiextensions_apiserver__pkg__apis__apiextensions__v1beta1__json_schema_props.rs.snap b/tests/snapshots/test_codegen__tests__test_k8s__io__k8s__apiextensions_apiserver__pkg__apis__apiextensions__v1beta1__json_schema_props.rs.snap
index 92fbc254a..883c742ef 100644
--- a/tests/snapshots/test_codegen__tests__test_k8s__io__k8s__apiextensions_apiserver__pkg__apis__apiextensions__v1beta1__json_schema_props.rs.snap
+++ b/tests/snapshots/test_codegen__tests__test_k8s__io__k8s__apiextensions_apiserver__pkg__apis__apiextensions__v1beta1__json_schema_props.rs.snap
@@ -19,8 +19,8 @@ pub struct JsonSchemaProps<Any> {
     #[serde(rename = "anyOf")]
     pub any_of: Option<Vec<crate::codegen::io::k8s::apiextensions_apiserver::pkg::apis::apiextensions::v1beta1::json_schema_props::JsonSchemaProps<Any>>>,
     pub default: Option<Any>,
-    pub definitions: Option<std::collections::BTreeMap<String, crate::codegen::io::k8s::apiextensions_apiserver::pkg::apis::apiextensions::v1beta1::json_schema_props::JsonSchemaProps<Any>>>,
-    pub dependencies: Option<std::collections::BTreeMap<String, Any>>,
+    pub definitions: Option<paperclip::v2::PropertiesMap<String, crate::codegen::io::k8s::apiextensions_apiserver::pkg::apis::apiextensions::v1beta1::json_schema_props::JsonSchemaProps<Any>>>,
+    pub dependencies: Option<paperclip::v2::PropertiesMap<String, Any>>,
     pub description: Option<String>,
     #[serde(rename = "enum")]
     pub enum_: Option<Vec<Any>>,
@@ -56,8 +56,8 @@ pub struct JsonSchemaProps<Any> {
     pub one_of: Option<Vec<crate::codegen::io::k8s::apiextensions_apiserver::pkg::apis::apiextensions::v1beta1::json_schema_props::JsonSchemaProps<Any>>>,
     pub pattern: Option<String>,
     #[serde(rename = "patternProperties")]
-    pub pattern_properties: Option<std::collections::BTreeMap<String, crate::codegen::io::k8s::apiextensions_apiserver::pkg::apis::apiextensions::v1beta1::json_schema_props::JsonSchemaProps<Any>>>,
-    pub properties: Option<std::collections::BTreeMap<String, crate::codegen::io::k8s::apiextensions_apiserver::pkg::apis::apiextensions::v1beta1::json_schema_props::JsonSchemaProps<Any>>>,
+    pub pattern_properties: Option<paperclip::v2::PropertiesMap<String, crate::codegen::io::k8s::apiextensions_apiserver::pkg::apis::apiextensions::v1beta1::json_schema_props::JsonSchemaProps<Any>>>,
+    pub properties: Option<paperclip::v2::PropertiesMap<String, crate::codegen::io::k8s::apiextensions_apiserver::pkg::apis::apiextensions::v1beta1::json_schema_props::JsonSchemaProps<Any>>>,
     pub required: Option<Vec<String>>,
     pub title: Option<String>,
     #[serde(rename = "type")]
@@ -151,13 +151,13 @@ impl<Any> JsonSchemaPropsBuilder<Any> {
 
     #[inline]
     pub fn definitions(mut self, value: impl Iterator<Item = (String, crate::codegen::io::k8s::apiextensions_apiserver::pkg::apis::apiextensions::v1beta1::json_schema_props::JsonSchemaProps<Any>)>) -> Self {
-        self.body.definitions = Some(value.map(|(key, value)| (key, value.into())).collect::<std::collections::BTreeMap<_, _>>().into());
+        self.body.definitions = Some(value.map(|(key, value)| (key, value.into())).collect::<paperclip::v2::PropertiesMap<_, _>>().into());
         self
     }
 
     #[inline]
     pub fn dependencies(mut self, value: impl Iterator<Item = (String, impl Into<Any>)>) -> Self {
-        self.body.dependencies = Some(value.map(|(key, value)| (key, value.into())).collect::<std::collections::BTreeMap<_, _>>().into());
+        self.body.dependencies = Some(value.map(|(key, value)| (key, value.into())).collect::<paperclip::v2::PropertiesMap<_, _>>().into());
         self
     }
 
@@ -295,13 +295,13 @@ impl<Any> JsonSchemaPropsBuilder<Any> {
 
     #[inline]
     pub fn pattern_properties(mut self, value: impl Iterator<Item = (String, crate::codegen::io::k8s::apiextensions_apiserver::pkg::apis::apiextensions::v1beta1::json_schema_props::JsonSchemaProps<Any>)>) -> Self {
-        self.body.pattern_properties = Some(value.map(|(key, value)| (key, value.into())).collect::<std::collections::BTreeMap<_, _>>().into());
+        self.body.pattern_properties = Some(value.map(|(key, value)| (key, value.into())).collect::<paperclip::v2::PropertiesMap<_, _>>().into());
         self
     }
 
     #[inline]
     pub fn properties(mut self, value: impl Iterator<Item = (String, crate::codegen::io::k8s::apiextensions_apiserver::pkg::apis::apiextensions::v1beta1::json_schema_props::JsonSchemaProps<Any>)>) -> Self {
-        self.body.properties = Some(value.map(|(key, value)| (key, value.into())).collect::<std::collections::BTreeMap<_, _>>().into());
+        self.body.properties = Some(value.map(|(key, value)| (key, value.into())).collect::<paperclip::v2::PropertiesMap<_, _>>().into());
         self
     }
 
diff --git a/tests/snapshots/test_codegen__tests__test_pet__pet.rs.snap b/tests/snapshots/test_codegen__tests__test_pet__pet.rs.snap
index 81811b7ec..394da0086 100644
--- a/tests/snapshots/test_codegen__tests__test_pet__pet.rs.snap
+++ b/tests/snapshots/test_codegen__tests__test_pet__pet.rs.snap
@@ -13,7 +13,7 @@ pub struct Pet<Any> {
     pub photo_urls: Option<Vec<String>>,
     pub tags: Option<Vec<crate::tag::Tag>>,
     #[serde(flatten)]
-    pub other_fields: Option<std::collections::BTreeMap<String, Any>>,
+    pub other_fields: Option<paperclip::v2::PropertiesMap<String, Any>>,
 }
 
 impl<Any: Default> Pet<Any> {
@@ -107,7 +107,7 @@ impl<Id, Name, Any> PetBuilder<Id, Name, Any> {
 
     #[inline]
     pub fn other_fields(mut self, value: impl Iterator<Item = (String, impl Into<Any>)>) -> Self {
-        self.body.other_fields = Some(value.map(|(key, value)| (key, value.into())).collect::<std::collections::BTreeMap<_, _>>().into());
+        self.body.other_fields = Some(value.map(|(key, value)| (key, value.into())).collect::<paperclip::v2::PropertiesMap<_, _>>().into());
         self
     }
 }
@@ -189,7 +189,7 @@ impl<XAuth, Id, Name, Any> PetPostBuilder<XAuth, Id, Name, Any> {
 
     #[inline]
     pub fn other_fields(mut self, value: impl Iterator<Item = (String, impl Into<Any>)>) -> Self {
-        self.inner.body.other_fields = Some(value.map(|(key, value)| (key, value.into())).collect::<std::collections::BTreeMap<_, _>>().into());
+        self.inner.body.other_fields = Some(value.map(|(key, value)| (key, value.into())).collect::<paperclip::v2::PropertiesMap<_, _>>().into());
         self
     }
 }
diff --git a/tests/test_app.rs b/tests/test_app.rs
index 148cb2c1e..1febe682f 100644
--- a/tests/test_app.rs
+++ b/tests/test_app.rs
@@ -5202,6 +5202,88 @@ fn test_schema_with_generics() {
     );
 }
 
+#[test]
+fn test_schema_properties_order() {
+    /// A good boy/girl.
+    #[derive(Apiv2Schema, Deserialize, Serialize)]
+    struct Dog {
+        /// Pick a good one.
+        name: String,
+        /// Be sure to chip them!
+        id: usize,
+        /// To each their own preferred one.
+        breed: String,
+    }
+
+    #[post("/echo")]
+    #[api_v2_operation]
+    async fn echo(body: web::Json<Dog>) -> Result<web::Json<Dog>, Error> {
+        Ok(body)
+    }
+
+    run_and_check_app(
+        || {
+            App::new()
+                .wrap_api()
+                .service(echo)
+                .with_raw_json_spec(|app, spec| {
+                    app.route(
+                        "/api/spec",
+                        web::get().to(move || {
+                            #[cfg(feature = "actix4")]
+                            {
+                                let spec = spec.clone();
+                                async move {
+                                    paperclip::actix::HttpResponseWrapper(
+                                        actix_web::HttpResponse::Ok().json(&spec),
+                                    )
+                                }
+                            }
+
+                            #[cfg(not(feature = "actix4"))]
+                            actix_web::HttpResponse::Ok().json(&spec)
+                        }),
+                    )
+                })
+                .build()
+        },
+        |addr| {
+            let resp = CLIENT
+                .get(&format!("http://{}/api/spec", addr))
+                .send()
+                .expect("request failed?");
+
+            assert_eq!(resp.status().as_u16(), 200);
+            let json = resp.json::<serde_json::Value>().expect("json error");
+
+            let properties = json
+                .as_object()
+                .expect("schema is not an object")
+                .get("definitions")
+                .expect("schema does not have definitions")
+                .as_object()
+                .expect("definitions is not an object")
+                .get("Dog")
+                .expect("no dog definition")
+                .as_object()
+                .expect("dog definition is not an object")
+                .get("properties")
+                .expect("no dog properties")
+                .as_object()
+                .expect("dog properties is not an object")
+                .keys()
+                .collect::<Vec<_>>();
+
+            #[cfg(feature = "preserve_order")]
+            let expected = ["name", "id", "breed"];
+            #[cfg(not(feature = "preserve_order"))]
+            let expected = ["breed", "id", "name"];
+
+            assert_eq!(properties, expected);
+        },
+    );
+}
+
 #[test]
 #[cfg(feature = "path-in-definition")]
 fn test_module_path_in_definition_name() {