diff --git a/src/main/resources/com/google/api/codegen/php/test.snip b/src/main/resources/com/google/api/codegen/php/test.snip
index 805b24d587..5f5de62d37 100644
--- a/src/main/resources/com/google/api/codegen/php/test.snip
+++ b/src/main/resources/com/google/api/codegen/php/test.snip
@@ -32,9 +32,7 @@
      */
     private function createCredentials()
     {
-        return $this->getMockBuilder(CredentialsWrapper::class)
-            ->disableOriginalConstructor()
-            ->getMock();
+        return $this->prophesize(CredentialsWrapper::class)->reveal();
     }
 
     /**
diff --git a/src/test/java/com/google/api/codegen/gapic/testdata/php/php_library.baseline b/src/test/java/com/google/api/codegen/gapic/testdata/php/php_library.baseline
index 28c7cfa318..0875d7ec78 100644
--- a/src/test/java/com/google/api/codegen/gapic/testdata/php/php_library.baseline
+++ b/src/test/java/com/google/api/codegen/gapic/testdata/php/php_library.baseline
@@ -5929,9 +5929,7 @@ class LibraryServiceClientTest extends GeneratedTest
      */
     private function createCredentials()
     {
-        return $this->getMockBuilder(CredentialsWrapper::class)
-            ->disableOriginalConstructor()
-            ->getMock();
+        return $this->prophesize(CredentialsWrapper::class)->reveal();
     }
 
     /**
@@ -8868,9 +8866,7 @@ class MyProtoClientTest extends GeneratedTest
      */
     private function createCredentials()
     {
-        return $this->getMockBuilder(CredentialsWrapper::class)
-            ->disableOriginalConstructor()
-            ->getMock();
+        return $this->prophesize(CredentialsWrapper::class)->reveal();
     }
 
     /**
diff --git a/src/test/java/com/google/api/codegen/gapic/testdata/php/php_longrunning.baseline b/src/test/java/com/google/api/codegen/gapic/testdata/php/php_longrunning.baseline
index ee68b02cf2..b2d9c18517 100644
--- a/src/test/java/com/google/api/codegen/gapic/testdata/php/php_longrunning.baseline
+++ b/src/test/java/com/google/api/codegen/gapic/testdata/php/php_longrunning.baseline
@@ -755,9 +755,7 @@ class OperationsClientTest extends GeneratedTest
      */
     private function createCredentials()
     {
-        return $this->getMockBuilder(CredentialsWrapper::class)
-            ->disableOriginalConstructor()
-            ->getMock();
+        return $this->prophesize(CredentialsWrapper::class)->reveal();
     }
 
     /**
diff --git a/src/test/java/com/google/api/codegen/gapic/testdata/php/php_no_path_templates.baseline b/src/test/java/com/google/api/codegen/gapic/testdata/php/php_no_path_templates.baseline
index ae0e953913..c8e107b951 100644
--- a/src/test/java/com/google/api/codegen/gapic/testdata/php/php_no_path_templates.baseline
+++ b/src/test/java/com/google/api/codegen/gapic/testdata/php/php_no_path_templates.baseline
@@ -396,9 +396,7 @@ class NoTemplatesApiServiceClientTest extends GeneratedTest
      */
     private function createCredentials()
     {
-        return $this->getMockBuilder(CredentialsWrapper::class)
-            ->disableOriginalConstructor()
-            ->getMock();
+        return $this->prophesize(CredentialsWrapper::class)->reveal();
     }
 
     /**
diff --git a/src/test/java/com/google/api/codegen/protoannotations/testdata/php_library.baseline b/src/test/java/com/google/api/codegen/protoannotations/testdata/php_library.baseline
index 8a1e687e4a..a7b52f7918 100644
--- a/src/test/java/com/google/api/codegen/protoannotations/testdata/php_library.baseline
+++ b/src/test/java/com/google/api/codegen/protoannotations/testdata/php_library.baseline
@@ -6958,9 +6958,7 @@ class LibraryServiceClientTest extends GeneratedTest
      */
     private function createCredentials()
     {
-        return $this->getMockBuilder(CredentialsWrapper::class)
-            ->disableOriginalConstructor()
-            ->getMock();
+        return $this->prophesize(CredentialsWrapper::class)->reveal();
     }
 
     /**
@@ -10254,9 +10252,7 @@ class MyProtoClientTest extends GeneratedTest
      */
     private function createCredentials()
     {
-        return $this->getMockBuilder(CredentialsWrapper::class)
-            ->disableOriginalConstructor()
-            ->getMock();
+        return $this->prophesize(CredentialsWrapper::class)->reveal();
     }
 
     /**
diff --git a/src/test/java/com/google/api/codegen/protoannotations/testdata/php_library_with_grpc_service_config.baseline b/src/test/java/com/google/api/codegen/protoannotations/testdata/php_library_with_grpc_service_config.baseline
index daff2c49b8..5e304559e7 100644
--- a/src/test/java/com/google/api/codegen/protoannotations/testdata/php_library_with_grpc_service_config.baseline
+++ b/src/test/java/com/google/api/codegen/protoannotations/testdata/php_library_with_grpc_service_config.baseline
@@ -6983,9 +6983,7 @@ class LibraryServiceClientTest extends GeneratedTest
      */
     private function createCredentials()
     {
-        return $this->getMockBuilder(CredentialsWrapper::class)
-            ->disableOriginalConstructor()
-            ->getMock();
+        return $this->prophesize(CredentialsWrapper::class)->reveal();
     }
 
     /**
@@ -10279,9 +10277,7 @@ class MyProtoClientTest extends GeneratedTest
      */
     private function createCredentials()
     {
-        return $this->getMockBuilder(CredentialsWrapper::class)
-            ->disableOriginalConstructor()
-            ->getMock();
+        return $this->prophesize(CredentialsWrapper::class)->reveal();
     }
 
     /**