diff --git a/src/python/src/grpc/_adapter/_call.h b/src/python/src/grpc/_adapter/_call.h
index fb9160901baf084b78e8a4905d33eb0166297b74..b4cf9d7ec99f969095938a865de42f90c8d5de3f 100644
--- a/src/python/src/grpc/_adapter/_call.h
+++ b/src/python/src/grpc/_adapter/_call.h
@@ -70,7 +70,7 @@ typedef struct {
   grpc_call *c_call;
 } Call;
 
-PyTypeObject pygrpc_CallType;
+extern PyTypeObject pygrpc_CallType;
 
 int pygrpc_add_call(PyObject *module);
 
diff --git a/src/python/src/grpc/_adapter/_channel.h b/src/python/src/grpc/_adapter/_channel.h
index afc0f80359d3fb6003f6de62541e5866f1fbad8e..65894939a23302911739d0fa119d15b4868c5751 100644
--- a/src/python/src/grpc/_adapter/_channel.h
+++ b/src/python/src/grpc/_adapter/_channel.h
@@ -42,7 +42,7 @@ typedef struct {
   grpc_channel *c_channel;
 } Channel;
 
-PyTypeObject pygrpc_ChannelType;
+extern PyTypeObject pygrpc_ChannelType;
 
 int pygrpc_add_channel(PyObject *module);
 
diff --git a/src/python/src/grpc/_adapter/_client_credentials.h b/src/python/src/grpc/_adapter/_client_credentials.h
index bb9f7f0c3a17a02fa4a5ecdf26353cd8fb652b2f..fe04016d20cf29e6a0d6464e346b423dabaf30c9 100644
--- a/src/python/src/grpc/_adapter/_client_credentials.h
+++ b/src/python/src/grpc/_adapter/_client_credentials.h
@@ -42,7 +42,7 @@ typedef struct {
   grpc_credentials *c_client_credentials;
 } ClientCredentials;
 
-PyTypeObject pygrpc_ClientCredentialsType;
+extern PyTypeObject pygrpc_ClientCredentialsType;
 
 int pygrpc_add_client_credentials(PyObject *module);
 
diff --git a/src/python/src/grpc/_adapter/_completion_queue.h b/src/python/src/grpc/_adapter/_completion_queue.h
index 9b377d15d9c5831d1eb5ea127981a9237c396dd9..516694daa19483340f82b2693811350130cd6d72 100644
--- a/src/python/src/grpc/_adapter/_completion_queue.h
+++ b/src/python/src/grpc/_adapter/_completion_queue.h
@@ -42,7 +42,7 @@ typedef struct {
   grpc_completion_queue *c_completion_queue;
 } CompletionQueue;
 
-PyTypeObject pygrpc_CompletionQueueType;
+extern PyTypeObject pygrpc_CompletionQueueType;
 
 int pygrpc_add_completion_queue(PyObject *module);
 
diff --git a/src/python/src/grpc/_adapter/_server_credentials.h b/src/python/src/grpc/_adapter/_server_credentials.h
index 6090404bd9561602b5af7f4cf7ce3fa2208693d0..75af9340897940b940d17318ec7df3fbe2f6c7ef 100644
--- a/src/python/src/grpc/_adapter/_server_credentials.h
+++ b/src/python/src/grpc/_adapter/_server_credentials.h
@@ -42,7 +42,7 @@ typedef struct {
   grpc_server_credentials *c_server_credentials;
 } ServerCredentials;
 
-PyTypeObject pygrpc_ServerCredentialsType;
+extern PyTypeObject pygrpc_ServerCredentialsType;
 
 int pygrpc_add_server_credentials(PyObject *module);