--- configure.orig	2011-11-11 21:59:26.000000000 +0100
+++ configure	2011-12-11 17:11:22.000000000 +0100
@@ -7360,9 +7360,9 @@
 			SAVED_LDFLAGS=$LDFLAGS
 			SAVED_LIBS=$LIBS
 
-			CFLAGS+=" $LIBPNG_CFLAGS"
-			LDFLAGS+=" $LIBPNG_LDFLAGS"
-			LIBS+=" $LIBPNG_LIBS"
+			CFLAGS="$CFLAGS $LIBPNG_CFLAGS"
+			LDFLAGS="$LDFLAGS $LIBPNG_LDFLAGS"
+			LIBS="$LIBS $LIBPNG_LIBS"
 
 			cat confdefs.h - <<_ACEOF >conftest.$ac_ext
 /* end confdefs.h.  */