--- a/common/autoconf/basics.m4	Tue Jan 31 20:06:23 2017 -0800
+++ b/common/autoconf/basics.m4	Thu Feb 02 12:05:51 2017 +0100
@@ -746,7 +746,8 @@
     fi
 
     # set SDKROOT too, Xcode tools will pick it up
-    AC_SUBST(SDKROOT,$SYSROOT)
+    SDKROOT="$SYSROOT"
+    AC_SUBST(SDKROOT)
   fi
 
   # Prepend the extra path to the global path
@@ -831,9 +832,10 @@
   CONFIGURESUPPORT_OUTPUTDIR="$OUTPUT_ROOT/configure-support"
   $MKDIR -p "$CONFIGURESUPPORT_OUTPUTDIR"
 
-  AC_SUBST(SPEC, $OUTPUT_ROOT/spec.gmk)
-  AC_SUBST(CONF_NAME, $CONF_NAME)
-  AC_SUBST(OUTPUT_ROOT, $OUTPUT_ROOT)
+  SPEC="$OUTPUT_ROOT/spec.gmk"
+  AC_SUBST(SPEC)
+  AC_SUBST(CONF_NAME)
+  AC_SUBST(OUTPUT_ROOT)
   AC_SUBST(CONFIGURESUPPORT_OUTPUTDIR)
 
   # The spec.gmk file contains all variables for the make system.