diff --git a/ChangeLog.md b/ChangeLog.md
index 12082659987..b39aee89faa 100644
--- a/ChangeLog.md
+++ b/ChangeLog.md
@@ -11,6 +11,7 @@ Modelerfour version: 4.15.378
 **Bug Fixes**
 
 - Fix duplicate type signatures in multiapi async config file  #727
+- Allowing single quote in regexp  #726
 
 ### 2020-06-23 - 5.1.0-preview.5
 Autorest Core version: 3.0.6287
diff --git a/autorest/codegen/models/primitive_schemas.py b/autorest/codegen/models/primitive_schemas.py
index 80945cd21ba..e54a99653af 100644
--- a/autorest/codegen/models/primitive_schemas.py
+++ b/autorest/codegen/models/primitive_schemas.py
@@ -19,7 +19,7 @@ def __init__(self, string: str) -> None:
         self.string = string
 
     def __repr__(self) -> str:
-        return f"r'{self.string}'"
+        return "r'{}'".format(self.string.replace('\'', '\\\''))
 
 
 class PrimitiveSchema(BaseSchema):
diff --git a/package.json b/package.json
index 4d33fb31359..21fa4aa62ca 100644
--- a/package.json
+++ b/package.json
@@ -27,7 +27,7 @@
   },
   "devDependencies": {
     "@autorest/autorest": "^3.0.0",
-    "@microsoft.azure/autorest.testserver": "^2.10.54"
+    "@microsoft.azure/autorest.testserver": "^2.10.55"
   },
   "files": [
     "autorest/**/*.py",
diff --git a/test/vanilla/Expected/AcceptanceTests/Validation/validation/aio/operations_async/_auto_rest_validation_test_operations_async.py b/test/vanilla/Expected/AcceptanceTests/Validation/validation/aio/operations_async/_auto_rest_validation_test_operations_async.py
index cd292ddefb0..734d1fc5b74 100644
--- a/test/vanilla/Expected/AcceptanceTests/Validation/validation/aio/operations_async/_auto_rest_validation_test_operations_async.py
+++ b/test/vanilla/Expected/AcceptanceTests/Validation/validation/aio/operations_async/_auto_rest_validation_test_operations_async.py
@@ -47,7 +47,7 @@ async def validation_of_method_parameters(
         url = self.validation_of_method_parameters.metadata['url']  # type: ignore
         path_format_arguments = {
             'subscriptionId': self._serialize.url("self._config.subscription_id", self._config.subscription_id, 'str'),
-            'resourceGroupName': self._serialize.url("resource_group_name", resource_group_name, 'str', max_length=10, min_length=3, pattern=r'[a-zA-Z0-9']+'),
+            'resourceGroupName': self._serialize.url("resource_group_name", resource_group_name, 'str', max_length=10, min_length=3, pattern=r'[a-zA-Z0-9\']+'),
             'id': self._serialize.url("id", id, 'int', maximum=1000, minimum=100, multiple=10),
         }
         url = self._client.format_url(url, **path_format_arguments)
diff --git a/test/vanilla/Expected/AcceptanceTests/Validation/validation/operations/_auto_rest_validation_test_operations.py b/test/vanilla/Expected/AcceptanceTests/Validation/validation/operations/_auto_rest_validation_test_operations.py
index 784f55cec78..146409d1d50 100644
--- a/test/vanilla/Expected/AcceptanceTests/Validation/validation/operations/_auto_rest_validation_test_operations.py
+++ b/test/vanilla/Expected/AcceptanceTests/Validation/validation/operations/_auto_rest_validation_test_operations.py
@@ -52,7 +52,7 @@ def validation_of_method_parameters(
         url = self.validation_of_method_parameters.metadata['url']  # type: ignore
         path_format_arguments = {
             'subscriptionId': self._serialize.url("self._config.subscription_id", self._config.subscription_id, 'str'),
-            'resourceGroupName': self._serialize.url("resource_group_name", resource_group_name, 'str', max_length=10, min_length=3, pattern=r'[a-zA-Z0-9']+'),
+            'resourceGroupName': self._serialize.url("resource_group_name", resource_group_name, 'str', max_length=10, min_length=3, pattern=r'[a-zA-Z0-9\']+'),
             'id': self._serialize.url("id", id, 'int', maximum=1000, minimum=100, multiple=10),
         }
         url = self._client.format_url(url, **path_format_arguments)