diff --git a/Source/cmTarget.cxx b/Source/cmTarget.cxx
index e063125a2..f8cf079ff 100644
--- a/Source/cmTarget.cxx
+++ b/Source/cmTarget.cxx
@@ -4037,7 +4037,7 @@ std::string cmTarget::GetFrameworkVersion() const
 }
 
 //----------------------------------------------------------------------------
-const char* cmTarget::GetExportMacro()
+const char* cmTarget::GetExportMacro() const
 {
   // Define the symbol for targets that export symbols.
   if(this->GetType() == cmTarget::SHARED_LIBRARY ||
diff --git a/Source/cmTarget.h b/Source/cmTarget.h
index d78fe3552..cbd5f5815 100644
--- a/Source/cmTarget.h
+++ b/Source/cmTarget.h
@@ -449,7 +449,7 @@ public:
 
   /** Get the macro to define when building sources in this target.
       If no macro should be defined null is returned.  */
-  const char* GetExportMacro();
+  const char* GetExportMacro() const;
 
   void GetCompileDefinitions(std::vector<std::string> &result,
                              const char *config) const;
@@ -678,7 +678,7 @@ private:
   bool HaveInstallRule;
   std::string InstallPath;
   std::string RuntimeInstallPath;
-  std::string ExportMacro;
+  mutable std::string ExportMacro;
   std::set<cmStdString> Utilities;
   bool RecordDependencies;
   mutable cmPropertyMap Properties;