diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 13a5a6c68..7c6a84246 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -6,7 +6,7 @@ on:
       - 'main'
 
 env:
-  BUILDER_VERSION: v0.9.59
+  BUILDER_VERSION: v0.9.61
   BUILDER_SOURCE: releases
   BUILDER_HOST: https://d19elf31gohf1l.cloudfront.net
   PACKAGE_NAME: aws-c-s3
diff --git a/include/aws/s3/s3_client.h b/include/aws/s3/s3_client.h
index beab10a66..84782f6aa 100644
--- a/include/aws/s3/s3_client.h
+++ b/include/aws/s3/s3_client.h
@@ -369,8 +369,9 @@ struct aws_s3_client_config {
     enum aws_s3_meta_request_tls_mode tls_mode;
 
     /* TLS Options to be used for each connection, if tls_mode is ENABLED. When compiling with BYO_CRYPTO, and tls_mode
-     * is ENABLED, this is required. Otherwise, this is optional. */
-    struct aws_tls_connection_options *tls_connection_options;
+     * is ENABLED, this is required. Otherwise, this is optional.
+     */
+    const struct aws_tls_connection_options *tls_connection_options;
 
     /**
      * Required.
@@ -387,7 +388,7 @@ struct aws_s3_client_config {
      *
      * TODO: deprecate this structure from auth, introduce a new S3 specific one.
      */
-    struct aws_signing_config_aws *signing_config;
+    const struct aws_signing_config_aws *signing_config;
 
     /**
      * Optional.
@@ -445,7 +446,7 @@ struct aws_s3_client_config {
      * If the connection_type is AWS_HPCT_HTTP_LEGACY, it will be converted to AWS_HPCT_HTTP_TUNNEL if tls_mode is
      * ENABLED. Otherwise, it will be converted to AWS_HPCT_HTTP_FORWARD.
      */
-    struct aws_http_proxy_options *proxy_options;
+    const struct aws_http_proxy_options *proxy_options;
 
     /**
      * Optional.
@@ -454,7 +455,7 @@ struct aws_s3_client_config {
      * configuration from environment.
      * Only works when proxy_options is not set. If both are set, configuration from proxy_options is used.
      */
-    struct proxy_env_var_settings *proxy_ev_settings;
+    const struct proxy_env_var_settings *proxy_ev_settings;
 
     /**
      * Optional.
@@ -466,7 +467,7 @@ struct aws_s3_client_config {
      * Optional.
      * Set keepalive to periodically transmit messages for detecting a disconnected peer.
      */
-    struct aws_s3_tcp_keep_alive_options *tcp_keep_alive_options;
+    const struct aws_s3_tcp_keep_alive_options *tcp_keep_alive_options;
 
     /**
      * Optional.
@@ -474,7 +475,7 @@ struct aws_s3_client_config {
      * If the transfer speed falls below the specified minimum_throughput_bytes_per_second, the operation is aborted.
      * If set to NULL, default values are used.
      */
-    struct aws_http_connection_monitoring_options *monitoring_options;
+    const struct aws_http_connection_monitoring_options *monitoring_options;
 
     /**
      * Enable backpressure and prevent response data from downloading faster than you can handle it.
@@ -572,7 +573,7 @@ struct aws_s3_checksum_config {
      *
      * If the response checksum was validated by client, the result will indicate which algorithm was picked.
      */
-    struct aws_array_list *validate_checksum_algorithms;
+    const struct aws_array_list *validate_checksum_algorithms;
 };
 
 /**
@@ -760,7 +761,7 @@ struct aws_s3_meta_request_options {
      * - Both Host and Endpoint is set - Host header must match Authority of
      *   Endpoint uri. Port and Scheme from endpoint is used.
      */
-    struct aws_uri *endpoint;
+    const struct aws_uri *endpoint;
 
     /**
      * Optional.
@@ -778,7 +779,7 @@ struct aws_s3_meta_request_options {
      * Set this hint to help the S3 client choose the best strategy for this particular file.
      * This is just used as an estimate, so it's okay to provide an approximate value if the exact size is unknown.
      */
-    uint64_t *object_size_hint;
+    const uint64_t *object_size_hint;
 };
 
 /* Result details of a meta request.
diff --git a/tests/s3_tester.c b/tests/s3_tester.c
index a81e74cc3..78575e154 100644
--- a/tests/s3_tester.c
+++ b/tests/s3_tester.c
@@ -475,7 +475,7 @@ int aws_s3_tester_bind_client(struct aws_s3_tester *tester, struct aws_s3_client
         config->region = g_test_s3_region;
     } else {
         if (config->signing_config) {
-            config->signing_config->region = config->region;
+            ((struct aws_signing_config_aws *)config->signing_config)->region = config->region;
         }
     }
     if (!config->signing_config) {