diff --git a/configure b/configure
index 2c938cf..9360a06 100755
--- a/configure
+++ b/configure
@@ -48,7 +48,7 @@ fi
 
 echo CC=$CC>config.mak
 echo CPPFLAGS=$CPPFLAGS>>config.mak
-echo CFLAGS=$CFLAGS>>config.mak
+[ -z "$CFLAGS" ] || echo CFLAGS=$CFLAGS>>config.mak
 echo prefix=$prefix>>config.mak
 echo exec_prefix=$exec_prefix>>config.mak
 echo bindir=$bindir>>config.mak