diff --git a/Source/cmGlobalGenerator.cxx b/Source/cmGlobalGenerator.cxx
index bd26b5fca..fbc578b26 100644
--- a/Source/cmGlobalGenerator.cxx
+++ b/Source/cmGlobalGenerator.cxx
@@ -1487,7 +1487,7 @@ void cmGlobalGenerator::FillLocalGeneratorToTargetMap()
         // Add dependencies of the included target.  An excluded
         // target may still be included if it is a dependency of a
         // non-excluded target.
-        TargetDependSet & tgtdeps = this->GetTargetDirectDepends(target);
+        TargetDependSet const& tgtdeps = this->GetTargetDirectDepends(target);
         for(TargetDependSet::const_iterator ti = tgtdeps.begin();
             ti != tgtdeps.end(); ++ti)
           {
@@ -1879,7 +1879,7 @@ void cmGlobalGenerator::AppendDirectoryForConfig(const char*, const char*,
 }
 
 //----------------------------------------------------------------------------
-cmGlobalGenerator::TargetDependSet &
+cmGlobalGenerator::TargetDependSet const&
 cmGlobalGenerator::GetTargetDirectDepends(cmTarget & target)
 {
   return this->TargetDependencies[&target];
diff --git a/Source/cmGlobalGenerator.h b/Source/cmGlobalGenerator.h
index 878be1143..9d5aa57a0 100644
--- a/Source/cmGlobalGenerator.h
+++ b/Source/cmGlobalGenerator.h
@@ -238,7 +238,7 @@ public:
 
   // what targets does the specified target depend on directly
   // via a target_link_libraries or add_dependencies
-  TargetDependSet & GetTargetDirectDepends(cmTarget & target);
+  TargetDependSet const& GetTargetDirectDepends(cmTarget & target);
 
   const std::map<cmStdString, std::vector<cmLocalGenerator*> >& GetProjectMap()
                                                const {return this->ProjectMap;}
diff --git a/Source/cmVisualStudio10TargetGenerator.cxx b/Source/cmVisualStudio10TargetGenerator.cxx
index 59e20d50c..2af70366e 100644
--- a/Source/cmVisualStudio10TargetGenerator.cxx
+++ b/Source/cmVisualStudio10TargetGenerator.cxx
@@ -1413,7 +1413,7 @@ void cmVisualStudio10TargetGenerator::WriteEvent(
 
 void cmVisualStudio10TargetGenerator::WriteProjectReferences()
 {
-  cmGlobalGenerator::TargetDependSet& depends
+  cmGlobalGenerator::TargetDependSet const& depends
     = this->GlobalGenerator->GetTargetDirectDepends(*this->Target);
   this->WriteString("<ItemGroup>\n", 1);
   for( cmGlobalGenerator::TargetDependSet::const_iterator i = depends.begin();