diff --git a/config/moz.build b/config/moz.build
index 13e616234dcf..70d93a63d90f 100644
--- a/config/moz.build
+++ b/config/moz.build
@@ -41,10 +41,10 @@ HOST_DEFINES = {
 include('stl-headers.mozbuild')
 if CONFIG['WRAP_STL_INCLUDES']:
     stl_compiler = None
-    if CONFIG['CC_TYPE'] in ('clang', 'gcc'):
-        stl_compiler = 'gcc'
-    elif CONFIG['CC_TYPE'] == 'clang-cl':
+    if CONFIG['OS_TARGET'] == 'WINNT':
         stl_compiler = 'msvc'
+    else:
+        stl_compiler = 'gcc'
 
     if stl_compiler:
         # Note that the 'stl_wrappers' folder is known to the build system as
@@ -67,7 +67,7 @@ if CONFIG['WRAP_STL_INCLUDES']:
     # NOTE: If we aren't wrapping STL includes, we're building part of the browser
     # which won't need this wrapper, such as L10N. Just don't try to generate the
     # wrapper in that case.
-    if CONFIG['OS_ARCH'] == 'WINNT':
+    if CONFIG['OS_TARGET'] == 'WINNT':
         GeneratedFile('../dist/stl_wrappers/windows.h',
                       script='make-windows-h-wrapper.py',
                       entry_point='generate',
diff --git a/old-configure.in b/old-configure.in
index c93385db7bf4..cda311573f09 100644
--- a/old-configure.in
+++ b/old-configure.in
@@ -206,8 +206,6 @@ case "$target" in
 
         WRAP_STL_INCLUDES=1
         STL_FLAGS="-I${DIST}/stl_wrappers"
-        CFLAGS="$CFLAGS -D_HAS_EXCEPTIONS=0"
-        CXXFLAGS="$CXXFLAGS -D_HAS_EXCEPTIONS=0"
     else
         # Check w32api version
         _W32API_MAJOR_VERSION=`echo $W32API_VERSION | $AWK -F\. '{ print $1 }'`
@@ -229,6 +227,9 @@ case "$target" in
         AC_DEFINE(STRSAFE_NO_DEPRECATE)
     fi # !GNU_CC
 
+    CFLAGS="$CFLAGS -D_HAS_EXCEPTIONS=0"
+    CXXFLAGS="$CXXFLAGS -D_HAS_EXCEPTIONS=0"
+
     AC_DEFINE_UNQUOTED(WINVER,0x$WINVER)
     AC_DEFINE_UNQUOTED(_WIN32_WINNT,0x$WINVER)
     # Require OS features provided by IE 8.0 (Win7)