diff --git a/source/adios2/toolkit/derived/Function.cpp b/source/adios2/toolkit/derived/Function.cpp
index 33d085878b..8bbf8e5a73 100644
--- a/source/adios2/toolkit/derived/Function.cpp
+++ b/source/adios2/toolkit/derived/Function.cpp
@@ -12,6 +12,10 @@ namespace adios2
 {
 namespace derived
 {
+std::map<adios2::detail::ExpressionOperator, OperatorFunctions> OpFunctions = {
+    {adios2::detail::ExpressionOperator::OP_ADD, {AddFunc, SameDimsFunc}},
+    {adios2::detail::ExpressionOperator::OP_CURL, {Curl3DFunc, CurlDimsFunc}},
+    {adios2::detail::ExpressionOperator::OP_MAGN, {MagnitudeFunc, SameDimsFunc}}};
 
 DerivedData AddFunc(std::vector<DerivedData> inputData, DataType type)
 {
diff --git a/source/adios2/toolkit/derived/Function.h b/source/adios2/toolkit/derived/Function.h
index f8f54c8562..5228895f72 100644
--- a/source/adios2/toolkit/derived/Function.h
+++ b/source/adios2/toolkit/derived/Function.h
@@ -31,10 +31,7 @@ DerivedData Curl3DFunc(std::vector<DerivedData> input, DataType type);
 Dims SameDimsFunc(std::vector<Dims> input);
 Dims CurlDimsFunc(std::vector<Dims> input);
 
-const std::map<adios2::detail::ExpressionOperator, OperatorFunctions> OpFunctions = {
-    {adios2::detail::ExpressionOperator::OP_ADD, {AddFunc, SameDimsFunc}},
-    {adios2::detail::ExpressionOperator::OP_CURL, {Curl3DFunc, CurlDimsFunc}},
-    {adios2::detail::ExpressionOperator::OP_MAGN, {MagnitudeFunc, SameDimsFunc}}};
+extern std::map<adios2::detail::ExpressionOperator, OperatorFunctions> OpFunctions;
 
 template <class T>
 T *ApplyOneToOne(std::vector<DerivedData> inputData, size_t dataSize,