diff --git a/paddle/fluid/platform/device_context.cc b/paddle/fluid/platform/device_context.cc
index 7d6c3412ce31f798354159ab41569f7b1bfcbfc6..80ffc680c2a26426dea2e96a5e285abe38543c79 100644
--- a/paddle/fluid/platform/device_context.cc
+++ b/paddle/fluid/platform/device_context.cc
@@ -167,7 +167,7 @@ class CudnnHolder {
     if (required_workspace_len > WorkspaceSize()) {
       ReallocateWorkspace(required_workspace_len);
     }
-    cudnn_func(workspace_->ptr());
+    cudnn_func(WorkspacePtr());
   }
 
   ~CudnnHolder() { PADDLE_ENFORCE(dynload::cudnnDestroy(cudnn_handle_)); }
@@ -181,6 +181,14 @@ class CudnnHolder {
     }
   }
 
+  void* WorkspacePtr() const {
+    if (workspace_ == nullptr) {
+      return nullptr;
+    } else {
+      return workspace_->ptr();
+    }
+  }
+
   void ReallocateWorkspace(size_t required_workspace_len) {
     if (required_workspace_len <= WorkspaceSize()) {
       return;
diff --git a/paddle/fluid/pybind/tensor_py.h b/paddle/fluid/pybind/tensor_py.h
index 0e5fd97951a96c3b021297414d4b482e9016a472..1b95ec66bd514e23001ea5e06b6b867749e16eb8 100644
--- a/paddle/fluid/pybind/tensor_py.h
+++ b/paddle/fluid/pybind/tensor_py.h
@@ -99,7 +99,7 @@ struct CastToPyBufferImpl<true, I, ARGS...> {
 
         py_buffer->shape = reinterpret_cast<Py_ssize_t *>(
             malloc(sizeof(Py_ssize_t) * tensor.dims().size()));
-        for (size_t i = 0; i < tensor.dims().size(); ++i) {
+        for (int i = 0; i < tensor.dims().size(); ++i) {
           py_buffer->shape[i] = tensor.dims()[i];
         }