diff --git a/source/adios2/toolkit/derived/Function.cpp b/source/adios2/toolkit/derived/Function.cpp
index da64e37f60..7cb032f750 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 d41aab6581..7554916851 100644
--- a/source/adios2/toolkit/derived/Function.h
+++ b/source/adios2/toolkit/derived/Function.h
@@ -34,10 +34,7 @@ T linear_interp(T *data, size_t index, size_t count, size_t stride = 1);
 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,