diff --git a/mkfiles.pl b/mkfiles.pl
index 75cb538b..9466ffec 100755
--- a/mkfiles.pl
+++ b/mkfiles.pl
@@ -1078,7 +1078,8 @@ if (defined $makefiles{'ac'}) {
     "\n".
     "CC = \@CC\@\n".
     "\n".
-    &splitline("CFLAGS = \@CFLAGS\@ \@CPPFLAGS\@ \@DEFS\@ \@GTK_CFLAGS\@ " .
+    &splitline("CFLAGS = \@CFLAGS\@ \@PUTTYCFLAGS\@ \@CPPFLAGS\@ " .
+               "\@DEFS\@ \@GTK_CFLAGS\@ " .
 	       (join " ", map {"-I$dirpfx$_"} @srcdirs))."\n".
     "XLDFLAGS = \@LDFLAGS\@ \@LIBS\@ \@GTK_LIBS\@\n".
     "ULDFLAGS = \@LDFLAGS\@ \@LIBS\@\n".
diff --git a/unix/configure.ac b/unix/configure.ac
index fc16350c..dcbc1535 100644
--- a/unix/configure.ac
+++ b/unix/configure.ac
@@ -11,8 +11,11 @@ AC_CONFIG_HEADERS([uxconfig.h:uxconfig.in])
 AC_PROG_INSTALL
 AC_PROG_CC
 if test "X$GCC" = Xyes; then
-    CFLAGS="$CFLAGS -Wall -Werror"
+    PUTTYCFLAGS="-Wall -Werror"
+else
+    PUTTYCFLAGS=""
 fi
+AC_SUBST(PUTTYCFLAGS)
 
 AC_ARG_WITH(gssapi,
 [  --without-gssapi        disable GSS-API support])