diff --git a/src/operator/contrib/multi_lamb.cc b/src/operator/contrib/multi_lamb.cc
index 6ddc4dfd6559..710908d9c23e 100644
--- a/src/operator/contrib/multi_lamb.cc
+++ b/src/operator/contrib/multi_lamb.cc
@@ -167,7 +167,7 @@ std::vector<std::string> LAMBParamToVector(uint32_t num_tensors,
   return ret;
 }
 
-inline uint32_t NumTensors(const nnvm::NodeAttrs& attrs) {
+static inline uint32_t NumTensors(const nnvm::NodeAttrs& attrs) {
   return static_cast<uint32_t>(dmlc::get<MultiLAMBParam>(attrs.parsed).num_tensors);
 }
 
diff --git a/src/operator/contrib/multi_lans.cc b/src/operator/contrib/multi_lans.cc
index 37d6001312c4..8cb90806af03 100644
--- a/src/operator/contrib/multi_lans.cc
+++ b/src/operator/contrib/multi_lans.cc
@@ -183,7 +183,7 @@ std::vector<std::string> LANSParamToVector(uint32_t num_tensors,
   return ret;
 }
 
-inline uint32_t NumTensors(const nnvm::NodeAttrs& attrs) {
+static inline uint32_t NumTensors(const nnvm::NodeAttrs& attrs) {
   return static_cast<uint32_t>(dmlc::get<MultiLANSParam>(attrs.parsed).num_tensors);
 }