diff --git a/src/configure.in b/src/configure.in
index 6e292c4..6bc8fd7 100644
--- a/src/configure.in
+++ b/src/configure.in
@@ -3241,9 +3241,10 @@
   fi
   dnl -D_FORTIFY_SOURCE=2 crashes Vim on strcpy(buf, "000") when buf is
   dnl declared as char x[1] but actually longer.  Introduced in gcc 4.0.
+  dnl Also remove duplicate _FORTIFY_SOURCE arguments.
   AC_MSG_CHECKING(whether we need -D_FORTIFY_SOURCE=1)
   if test "$gccmajor" -gt "3"; then
-    CFLAGS=`echo "$CFLAGS -D_FORTIFY_SOURCE=1" | sed -e 's/-Wp,-D_FORTIFY_SOURCE=2//g' -e 's/-D_FORTIFY_SOURCE=2//g'`
+    CFLAGS=`echo "$CFLAGS" | sed -e 's/-Wp,-D_FORTIFY_SOURCE=.//g' -e 's/-D_FORTIFY_SOURCE=.//g' -e 's/$/ -D_FORTIFY_SOURCE=1/'`
     AC_MSG_RESULT(yes)
   else
     AC_MSG_RESULT(no)