diff --git a/muparser-2.2.5/include/muParserCallback.h b/muparser-2.2.5/include/muParserCallback.h
index 5621c6d66..a2cb4039c 100644
--- a/muparser-2.2.5/include/muParserCallback.h
+++ b/muparser-2.2.5/include/muParserCallback.h
@@ -61,7 +61,6 @@ class ParserCallback final {
     ParserCallback();
     ParserCallback(const ParserCallback& a_Fun);
 
-    bool IsOptimizable() const;
     void* GetAddr() const;
     ECmdCode GetCode() const;
     ETypeCode GetType() const;
@@ -82,7 +81,6 @@ class ParserCallback final {
     EOprtAssociativity m_eOprtAsct;  ///< Operator associativity; Valid only for binary operators
     ECmdCode m_iCode;
     ETypeCode m_iType;
-    bool m_bAllowOpti;  ///< Flag indication optimizeability
 };
 
 //------------------------------------------------------------------------------
diff --git a/muparser-2.2.5/src/muParserCallback.cpp b/muparser-2.2.5/src/muParserCallback.cpp
index 2867f0658..ab06b4c17 100644
--- a/muparser-2.2.5/src/muParserCallback.cpp
+++ b/muparser-2.2.5/src/muParserCallback.cpp
@@ -128,21 +128,13 @@ ParserCallback::ParserCallback()
       m_iPri(-1),
       m_eOprtAsct(oaNONE),
       m_iCode(cmUNKNOWN),
-      m_iType(tpVOID),
-      m_bAllowOpti(0) {}
+      m_iType(tpVOID) {}
 
 //---------------------------------------------------------------------------
 /** \brief Copy constructor.
 */
 ParserCallback::ParserCallback(const ParserCallback& ref) = default;
 
-//---------------------------------------------------------------------------
-/** \brief Return tru if the function is conservative.
-
-    Conservative functions return always the same result for the same argument.
-*/
-bool ParserCallback::IsOptimizable() const { return m_bAllowOpti; }
-
 //---------------------------------------------------------------------------
 /** \brief Get the callback address for the parser function.