--- a/configure.in
+++ b/configure.in
@@ -410,40 +410,37 @@ dnl Special win32 checks
 dnl ========================================================
 
 MOZ_ARG_ENABLE_BOOL(metro,
 [  --enable-metro           Enable Windows Metro build targets],
     MOZ_METRO=1,
     MOZ_METRO=)
 if test -n "$MOZ_METRO"; then
     AC_DEFINE(MOZ_METRO)
-    # Target the Windows 8 Kit
-    WINSDK_TARGETVER=602
-    WINVER=502
     # toolkit/library/makefile.in needs these, see nsDllMain.
     CRTDLLVERSION=110
     CRTEXPDLLVERSION=1-1-0
-else
-    # Target the Windows 7 SDK by default
-    WINSDK_TARGETVER=601
-    WINVER=502
 fi
 
 AC_SUBST(CRTDLLVERSION)
 AC_SUBST(CRTEXPDLLVERSION)
 
+# Target the Windows 8.1 SDK by default
+WINSDK_TARGETVER=603
+WINVER=502
+
 MOZ_ARG_WITH_STRING(windows-version,
 [  --with-windows-version=WINSDK_TARGETVER
-                          Windows SDK version to target. Lowest version
-                          currently allowed is 601 (Win7), highest is 602 (Win8)],
+                          Windows SDK version to target. Win8.1 (603) is
+                          currently the minimum supported version.],
   WINSDK_TARGETVER=$withval)
 
-# Currently only two sdk versions allowed, 601 and 602
+# Currently only version 603 is allowed
 case "$WINSDK_TARGETVER" in
-601|602)
+603)
     MOZ_WINSDK_TARGETVER=0${WINSDK_TARGETVER}0000
     ;;
 
 *)
     AC_MSG_ERROR([Invalid value for --with-windows-version ($WINSDK_TARGETVER)]);
     ;;
 esac
 
@@ -680,17 +677,17 @@ case "$target" in
                 ;;
             esac
         fi
 
         # strsafe.h on mingw uses macros for function deprecation that pollutes namespace
         # causing problems with local implementations with the same name.
         AC_DEFINE(STRSAFE_NO_DEPRECATE)
 
-        MOZ_WINSDK_MAXVER=0x06020000
+        MOZ_WINSDK_MAXVER=0x06030000
     fi # !GNU_CC
 
     AC_DEFINE_UNQUOTED(WINVER,0x$WINVER)
     AC_DEFINE_UNQUOTED(_WIN32_WINNT,0x$WINVER)
     # Require OS features provided by IE 6.0 SP2 (XP SP2)
     AC_DEFINE_UNQUOTED(_WIN32_IE,0x0603)
 
     # If the maximum version supported by this SDK is lower than the target

--- a/js/src/configure.in
+++ b/js/src/configure.in
@@ -341,34 +341,31 @@ dnl Special win32 checks
 dnl ========================================================
 
 MOZ_ARG_ENABLE_BOOL(metro,
 [  --enable-metro           Enable Windows Metro build targets],
     MOZ_METRO=1,
     MOZ_METRO=)
 if test -n "$MOZ_METRO"; then
     AC_DEFINE(MOZ_METRO)
-    # Target the Windows 8 Kit
-    WINSDK_TARGETVER=602
-    WINVER=502
-else
-    # Target the Windows 7 SDK by default
-    WINSDK_TARGETVER=601
-    WINVER=502
 fi
 
+# Target the Windows 8.1 SDK by default
+WINSDK_TARGETVER=603
+WINVER=502
+
 MOZ_ARG_WITH_STRING(windows-version,
 [  --with-windows-version=WINSDK_TARGETVER
-                          Windows SDK version to target. Lowest version
-                          currently allowed is 601, highest is 602],
+                          Windows SDK version to target. Win8.1 (603) is
+                          currently the minimum supported version.],
   WINSDK_TARGETVER=$withval)
 
-# Currently only two sdk versions allowed, 601 and 602
+# Currently only version 603 is allowed
 case "$WINSDK_TARGETVER" in
-601|602)
+603)
     MOZ_WINSDK_TARGETVER=0${WINSDK_TARGETVER}0000
     ;;
 
 *)
     AC_MSG_ERROR([Invalid value for --with-windows-version ($WINSDK_TARGETVER)]);
     ;;
 esac
 
@@ -490,17 +487,17 @@ case "$target" in
                 "$_WINDRES_MINOR_VERSION" -lt "$WINDRES_MINOR_VERSION" -o \
                 "$_WINDRES_MAJOR_VERSION" -eq "$WINDRES_MAJOR_VERSION" -a \
                 "$_WINDRES_MINOR_VERSION" -eq "$WINDRES_MINOR_VERSION" -a \
                 "$_WINDRES_RELEASE_VERSION" -lt "$WINDRES_RELEASE_VERSION"
         then
             AC_MSG_ERROR([windres version $WINDRES_VERSION or higher is required to build.])
         fi
 
-        MOZ_WINSDK_MAXVER=0x06010000
+        MOZ_WINSDK_MAXVER=0x06030000
     fi # !GNU_CC
 
     AC_DEFINE_UNQUOTED(WINVER,0x$WINVER)
     AC_DEFINE_UNQUOTED(_WIN32_WINNT,0x$WINVER)
     # Require OS features provided by IE 6.0 SP2 (XP SP2)
     AC_DEFINE_UNQUOTED(_WIN32_IE,0x0603)
 
     # If the maximum version supported by this SDK is lower than the target