diff --git a/Source/cmMakefileTargetGenerator.cxx b/Source/cmMakefileTargetGenerator.cxx
index 3161abaf5..fdca7f72b 100644
--- a/Source/cmMakefileTargetGenerator.cxx
+++ b/Source/cmMakefileTargetGenerator.cxx
@@ -373,7 +373,7 @@ void cmMakefileTargetGenerator::WriteTargetLanguageFlags()
 //----------------------------------------------------------------------------
 void
 cmMakefileTargetGenerator::MacOSXContentGeneratorType::operator()
-  (cmSourceFile& source, const char* pkgloc)
+  (cmSourceFile const& source, const char* pkgloc)
 {
   // Skip OS X content when not building a Framework or Bundle.
   if(!this->Generator->GetTarget()->IsBundleOnApple())
diff --git a/Source/cmMakefileTargetGenerator.h b/Source/cmMakefileTargetGenerator.h
index 97c58b982..f59bd9ba4 100644
--- a/Source/cmMakefileTargetGenerator.h
+++ b/Source/cmMakefileTargetGenerator.h
@@ -81,7 +81,7 @@ protected:
     MacOSXContentGeneratorType(cmMakefileTargetGenerator* gen) :
       Generator(gen) {}
 
-    void operator()(cmSourceFile& source, const char* pkgloc);
+    void operator()(cmSourceFile const& source, const char* pkgloc);
 
   private:
     cmMakefileTargetGenerator* Generator;
diff --git a/Source/cmNinjaTargetGenerator.cxx b/Source/cmNinjaTargetGenerator.cxx
index ed3782c2a..149b12915 100644
--- a/Source/cmNinjaTargetGenerator.cxx
+++ b/Source/cmNinjaTargetGenerator.cxx
@@ -733,7 +733,7 @@ cmNinjaTargetGenerator
 //----------------------------------------------------------------------------
 void
 cmNinjaTargetGenerator::MacOSXContentGeneratorType::operator()(
-  cmSourceFile& source, const char* pkgloc)
+  cmSourceFile const& source, const char* pkgloc)
 {
   // Skip OS X content when not building a Framework or Bundle.
   if(!this->Generator->GetTarget()->IsBundleOnApple())
diff --git a/Source/cmNinjaTargetGenerator.h b/Source/cmNinjaTargetGenerator.h
index e66e55fef..900e2bd1d 100644
--- a/Source/cmNinjaTargetGenerator.h
+++ b/Source/cmNinjaTargetGenerator.h
@@ -129,7 +129,7 @@ protected:
     MacOSXContentGeneratorType(cmNinjaTargetGenerator* g) :
       Generator(g)  {}
 
-    void operator()(cmSourceFile& source, const char* pkgloc);
+    void operator()(cmSourceFile const& source, const char* pkgloc);
 
   private:
     cmNinjaTargetGenerator* Generator;
diff --git a/Source/cmOSXBundleGenerator.h b/Source/cmOSXBundleGenerator.h
index 95b4aef6c..5acdd9f27 100644
--- a/Source/cmOSXBundleGenerator.h
+++ b/Source/cmOSXBundleGenerator.h
@@ -44,7 +44,8 @@ public:
   struct MacOSXContentGeneratorType
   {
     virtual ~MacOSXContentGeneratorType() {}
-    virtual void operator()(cmSourceFile& source, const char* pkgloc) = 0;
+    virtual void operator()(cmSourceFile const& source,
+                            const char* pkgloc) = 0;
   };
 
   void GenerateMacOSXContentStatements(