diff --git a/src/operator/nn/mkldnn/mkldnn_base-inl.h b/src/operator/nn/mkldnn/mkldnn_base-inl.h
index e367f42c188e..18ef3f3e767b 100644
--- a/src/operator/nn/mkldnn/mkldnn_base-inl.h
+++ b/src/operator/nn/mkldnn/mkldnn_base-inl.h
@@ -60,7 +60,7 @@
 #include "mxnet/op_attr_types.h"
 using namespace mkldnn;
 namespace mxnet {
-extern bool EnableMkldnnWarnGenerated();
+
 // =====  CpuEngine =======================================
 // cpu_engine singleton
 class CpuEngine {