diff --git a/README.md b/README.md
index bfc1489..cf9433c 100644
--- a/README.md
+++ b/README.md
@@ -71,7 +71,7 @@ type Person struct {
 This package currently provides the following checkers:
 
 - [alphanumeric](doc/checkers/alphanumeric.md) checks if the given string consists of only alphanumeric characters.
-- [ASCII](doc/checkers/ASCII.md) checks if the given string consists of only ASCII characters.
+- [ascii](doc/checkers/ascii.md) checks if the given string consists of only ASCII characters.
 - [cidr](doc/checkers/cidr.md) checker checks if the value is a valid CIDR notation IP address and prefix length.
 - [digits](doc/checkers/digits.md) checks if the given string consists of only digit characters.
 - [email](doc/checkers/email.md) checks if the given string is an email address.
diff --git a/ascii.go b/ascii.go
index d259c68..e06c171 100644
--- a/ascii.go
+++ b/ascii.go
@@ -6,7 +6,7 @@ import (
 )
 
 // CheckerASCII is the name of the checker.
-const CheckerASCII = "ASCII"
+const CheckerASCII = "ascii"
 
 // ResultNotASCII indicates that the given string contains non-ASCII characters.
 const ResultNotASCII = "NOT_ASCII"
diff --git a/ascii_test.go b/ascii_test.go
index bc5eb72..de2a9ea 100644
--- a/ascii_test.go
+++ b/ascii_test.go
@@ -18,7 +18,7 @@ func TestCheckASCIINonString(t *testing.T) {
 	defer FailIfNoPanic(t)
 
 	type User struct {
-		Age int `checkers:"ASCII"`
+		Age int `checkers:"ascii"`
 	}
 
 	user := &User{}
@@ -28,7 +28,7 @@ func TestCheckASCIINonString(t *testing.T) {
 
 func TestCheckASCIIInvalid(t *testing.T) {
 	type User struct {
-		Username string `checkers:"ASCII"`
+		Username string `checkers:"ascii"`
 	}
 
 	user := &User{
@@ -43,7 +43,7 @@ func TestCheckASCIIInvalid(t *testing.T) {
 
 func TestCheckASCIIValid(t *testing.T) {
 	type User struct {
-		Username string `checkers:"ASCII"`
+		Username string `checkers:"ascii"`
 	}
 
 	user := &User{
diff --git a/checker_test.go b/checker_test.go
index 8c93d88..b3e5b80 100644
--- a/checker_test.go
+++ b/checker_test.go
@@ -2,6 +2,7 @@ package checker
 
 import (
 	"reflect"
+	"strings"
 	"testing"
 )
 
@@ -148,6 +149,14 @@ func TestNumberOfFloat(t *testing.T) {
 	}
 }
 
+func TestCheckerNamesAreLowerCase(t *testing.T) {
+	for checker, _ := range makers {
+		if strings.ToLower(checker) != checker {
+			t.Fail()
+		}
+	}
+}
+
 func BenchmarkCheck(b *testing.B) {
 	type Address struct {
 		Street string `checkers:"required"`
diff --git a/doc/checkers/ascii.md b/doc/checkers/ascii.md
index 8ad0cec..8f7efe9 100644
--- a/doc/checkers/ascii.md
+++ b/doc/checkers/ascii.md
@@ -1,10 +1,10 @@
 # ASCII Checker
 
-The ```ASCII``` checker checks if the given string consists of only ASCII characters. If the string contains non-ASCII characters, the checker will return the ```NOT_ASCII``` result. Here is an example:
+The ```ascii``` checker checks if the given string consists of only ASCII characters. If the string contains non-ASCII characters, the checker will return the ```NOT_ASCII``` result. Here is an example:
 
 ```golang
 type User struct {
-  Username string `checkers:"ASCII"`
+  Username string `checkers:"ascii"`
 }
 
 user := &User{
@@ -17,7 +17,7 @@ if !valid {
 }
 ```
 
-In your custom checkers, you can call the ```ASCII``` checker function ```IsASCII``` to validate the user input. Here is an example:
+In your custom checkers, you can call the ```ascii``` checker function ```IsASCII``` to validate the user input. Here is an example:
 
 ```golang
 result := IsASCII("Checker")