diff --git a/Source/cmGlobalGenerator.cxx b/Source/cmGlobalGenerator.cxx
index 1cbd423e4..bd26b5fca 100644
--- a/Source/cmGlobalGenerator.cxx
+++ b/Source/cmGlobalGenerator.cxx
@@ -2068,20 +2068,27 @@ void cmGlobalGenerator::CheckRuleHashes()
   std::string pfile = home;
   pfile += this->GetCMakeInstance()->GetCMakeFilesDirectory();
   pfile += "/CMakeRuleHashes.txt";
+  this->CheckRuleHashes(pfile, home);
+  this->WriteRuleHashes(pfile);
+#endif
+}
 
+//----------------------------------------------------------------------------
+void cmGlobalGenerator::CheckRuleHashes(std::string const& pfile,
+                                        std::string const& home)
+{
 #if defined(_WIN32) || defined(__CYGWIN__)
   std::ifstream fin(pfile.c_str(), std::ios::in | std::ios::binary);
 #else
   std::ifstream fin(pfile.c_str(), std::ios::in);
 #endif
-  bool goodStream = true;
   if(!fin)
     {
-    goodStream = false;
+    return;
     }
   std::string line;
   std::string fname;
-  while(goodStream && cmSystemTools::GetLineFromStream(fin, line))
+  while(cmSystemTools::GetLineFromStream(fin, line))
     {
     // Line format is a 32-byte hex string followed by a space
     // followed by a file name (with no escaping).
@@ -2127,7 +2134,11 @@ void cmGlobalGenerator::CheckRuleHashes()
         }
       }
     }
+}
 
+//----------------------------------------------------------------------------
+void cmGlobalGenerator::WriteRuleHashes(std::string const& pfile)
+{
   // Now generate a new persistence file with the current hashes.
   if(this->RuleHashes.empty())
     {
@@ -2144,7 +2155,6 @@ void cmGlobalGenerator::CheckRuleHashes()
       fout << " " << rhi->first << "\n";
       }
     }
-#endif
 }
 
 //----------------------------------------------------------------------------
diff --git a/Source/cmGlobalGenerator.h b/Source/cmGlobalGenerator.h
index b7b4324be..878be1143 100644
--- a/Source/cmGlobalGenerator.h
+++ b/Source/cmGlobalGenerator.h
@@ -335,6 +335,8 @@ private:
   struct RuleHash { char Data[32]; };
   std::map<cmStdString, RuleHash> RuleHashes;
   void CheckRuleHashes();
+  void CheckRuleHashes(std::string const& pfile, std::string const& home);
+  void WriteRuleHashes(std::string const& pfile);
 
   void WriteSummary();
   void WriteSummary(cmTarget* target);