diff --git a/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/AbstractCSharpCodegen.java b/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/AbstractCSharpCodegen.java
index 85cc92c65e1346c2b022a3a77f4c243fbccf0d3e..3aedf18f13f0d3570631058f5f6f1dd3efd01817 100644
--- a/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/AbstractCSharpCodegen.java
+++ b/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/AbstractCSharpCodegen.java
@@ -206,8 +206,12 @@ public abstract class AbstractCSharpCodegen extends DefaultCodegen implements Co
 
     public void useDateTimeOffset(boolean flag) {
         this.useDateTimeOffsetFlag = flag;
-        if (flag) typeMapping.put("datetime", "DateTimeOffset?");
-        else typeMapping.put("datetime", "DateTime?");
+        if (flag) {
+            typeMapping.put("DateTime", "DateTimeOffset?");
+        }
+        else {
+            typeMapping.put("DateTime", "DateTime?");
+        }
     }
 
     @Override
diff --git a/samples/client/petstore/csharp/OpenAPIClientNet35/.openapi-generator/VERSION b/samples/client/petstore/csharp/OpenAPIClientNet35/.openapi-generator/VERSION
index e24c1f857e01d247fd3e2c824f7a1153108cd342..d077ffb477a49179c7e67ca2a9fec020920b18da 100644
--- a/samples/client/petstore/csharp/OpenAPIClientNet35/.openapi-generator/VERSION
+++ b/samples/client/petstore/csharp/OpenAPIClientNet35/.openapi-generator/VERSION
@@ -1 +1 @@
-3.3.3-SNAPSHOT
\ No newline at end of file
+3.3.4-SNAPSHOT
\ No newline at end of file
diff --git a/samples/client/petstore/csharp/OpenAPIClientNet40/.openapi-generator/VERSION b/samples/client/petstore/csharp/OpenAPIClientNet40/.openapi-generator/VERSION
index e24c1f857e01d247fd3e2c824f7a1153108cd342..d077ffb477a49179c7e67ca2a9fec020920b18da 100644
--- a/samples/client/petstore/csharp/OpenAPIClientNet40/.openapi-generator/VERSION
+++ b/samples/client/petstore/csharp/OpenAPIClientNet40/.openapi-generator/VERSION
@@ -1 +1 @@
-3.3.3-SNAPSHOT
\ No newline at end of file
+3.3.4-SNAPSHOT
\ No newline at end of file
diff --git a/samples/client/petstore/csharp/OpenAPIClientNetStandard/.openapi-generator/VERSION b/samples/client/petstore/csharp/OpenAPIClientNetStandard/.openapi-generator/VERSION
index e24c1f857e01d247fd3e2c824f7a1153108cd342..d077ffb477a49179c7e67ca2a9fec020920b18da 100644
--- a/samples/client/petstore/csharp/OpenAPIClientNetStandard/.openapi-generator/VERSION
+++ b/samples/client/petstore/csharp/OpenAPIClientNetStandard/.openapi-generator/VERSION
@@ -1 +1 @@
-3.3.3-SNAPSHOT
\ No newline at end of file
+3.3.4-SNAPSHOT
\ No newline at end of file
diff --git a/samples/client/petstore/csharp/OpenAPIClientWithPropertyChanged/.openapi-generator/VERSION b/samples/client/petstore/csharp/OpenAPIClientWithPropertyChanged/.openapi-generator/VERSION
index e24c1f857e01d247fd3e2c824f7a1153108cd342..d077ffb477a49179c7e67ca2a9fec020920b18da 100644
--- a/samples/client/petstore/csharp/OpenAPIClientWithPropertyChanged/.openapi-generator/VERSION
+++ b/samples/client/petstore/csharp/OpenAPIClientWithPropertyChanged/.openapi-generator/VERSION
@@ -1 +1 @@
-3.3.3-SNAPSHOT
\ No newline at end of file
+3.3.4-SNAPSHOT
\ No newline at end of file