diff -p -up comm-release/mozilla/configure.in.subdir-optflags comm-release/mozilla/configure.in
--- comm-release/mozilla/configure.in.subdir-optflags	2012-11-18 11:19:31.000000000 +0100
+++ comm-release/mozilla/configure.in	2012-11-25 03:45:58.283701984 +0100
@@ -6730,7 +6730,7 @@ MOZ_ARG_ENABLE_STRING(optimize,
 [ if test "$enableval" != "no"; then
     MOZ_OPTIMIZE=1
     if test -n "$enableval" -a "$enableval" != "yes"; then
-        MOZ_OPTIMIZE_FLAGS=`echo "$enableval" | sed -e 's|\\\ | |g'`
+        MOZ_OPTIMIZE_FLAGS=`echo "$enableval" | sed -e 's|\\\\\\\ | |g'`
         MOZ_OPTIMIZE=2
     fi
 else
diff -p -up comm-release/mozilla/js/src/configure.in.subdir-optflags comm-release/mozilla/js/src/configure.in
--- comm-release/mozilla/js/src/configure.in.subdir-optflags	2012-11-18 11:19:38.000000000 +0100
+++ comm-release/mozilla/js/src/configure.in	2012-11-25 14:48:00.437914639 +0100
@@ -3352,7 +3352,7 @@ MOZ_ARG_ENABLE_STRING(debug,
          ENABLE_METHODJIT_SPEW=1
     fi
     if test -n "$enableval" -a "$enableval" != "yes"; then
-        MOZ_DEBUG_FLAGS=`echo $enableval | sed -e 's|\\\ | |g'`
+        MOZ_DEBUG_FLAGS=`echo $enableval | sed -e 's|\\\\\\\ | |g'`
         _MOZ_DEBUG_FLAGS_SET=1
     fi
   else
@@ -3403,7 +3403,7 @@ MOZ_ARG_ENABLE_STRING(optimize,
 [ if test "$enableval" != "no"; then
     MOZ_OPTIMIZE=1
     if test -n "$enableval" -a "$enableval" != "yes"; then
-        MOZ_OPTIMIZE_FLAGS=`echo "$enableval" | sed -e 's|\\\ | |g'`
+        MOZ_OPTIMIZE_FLAGS=`echo "$enableval" | sed -e 's|\\\\\\\ | |g'`
         MOZ_OPTIMIZE=2
     fi
 else
@@ -3446,7 +3446,7 @@ MOZ_ARG_ENABLE_STRING(debug-symbols,
       MOZ_DEBUG_SYMBOLS=1
       if test -n "$enableval" -a "$enableval" != "yes"; then
           if test -z "$_MOZ_DEBUG_FLAGS_SET"; then
-              MOZ_DEBUG_FLAGS=`echo $enableval | sed -e 's|\\\ | |g'`
+              MOZ_DEBUG_FLAGS=`echo $enableval | sed -e 's|\\\\\\\ | |g'`
           else
               AC_MSG_ERROR([--enable-debug-symbols flags cannot be used with --enable-debug flags])
           fi