diff --git a/Modules/Platform/Darwin.cmake b/Modules/Platform/Darwin.cmake
index 5f14228f4..348abfc75 100644
--- a/Modules/Platform/Darwin.cmake
+++ b/Modules/Platform/Darwin.cmake
@@ -44,6 +44,7 @@ IF(EXISTS /Developer/SDKs/MacOSX10.4u.sdk)
   # now put _CMAKE_OSX_MACHINE into the cache
   SET(CMAKE_OSX_ARCHITECTURES ${_CMAKE_OSX_MACHINE}
     CACHE STRING "Build architectures for OSX")
+  SET(CMAKE_OSX_ARCHITECTURES_DEFAULT ${_CMAKE_OSX_MACHINE})
 ENDIF(EXISTS /Developer/SDKs/MacOSX10.4u.sdk)
 
 
diff --git a/Source/cmLocalGenerator.cxx b/Source/cmLocalGenerator.cxx
index acaaad50b..1e9c55ab8 100644
--- a/Source/cmLocalGenerator.cxx
+++ b/Source/cmLocalGenerator.cxx
@@ -1941,14 +1941,31 @@ void cmLocalGenerator::AddLanguageFlags(std::string& flags,
       std::vector<std::string> archs;
       cmSystemTools::ExpandListArgument(std::string(osxArch),
                                         archs);
-      for( std::vector<std::string>::iterator i = archs.begin();
-           i != archs.end(); ++i)
+      bool addArchFlag = true;
+      if(archs.size() == 1)
         {
-        flags += " -arch ";
-        flags += *i;
+        const char* archOrig = 
+          this->Makefile->GetSafeDefinition("CMAKE_OSX_ARCHITECTURE_DEFAULT");
+        if(archs[0] == archOrig)
+          {
+          addArchFlag = false;
+          }
+        }
+      // if there is more than one arch add the -arch and
+      // -isysroot flags, or if there is one arch flag, but
+      // it is not the default -arch flag for the system, then
+      // add it.  Otherwize do not add -arch and -isysroot
+      if(addArchFlag)
+        {
+        for( std::vector<std::string>::iterator i = archs.begin();
+             i != archs.end(); ++i)
+          {
+          flags += " -arch ";
+          flags += *i;
+          }
+        flags += " -isysroot ";
+        flags += sysroot;
         }
-      flags += " -isysroot ";
-      flags += sysroot;
       }
     }
   this->AddConfigVariableFlags(flags, flagsVar.c_str(), config);