diff --git a/gcc/config/i386/i386.c b/gcc/config/i386/i386.c
index 6153a3a9a53..337228bc145 100644
--- a/gcc/config/i386/i386.c
+++ b/gcc/config/i386/i386.c
@@ -1759,6 +1759,8 @@ output_fp_cc0_set (insn)
     return "sahf";
 
   next = next_cc0_user (insn);
+  if (next == NULL_RTX)
+    abort ();
 
   if (GET_CODE (next) == JUMP_INSN
       && GET_CODE (PATTERN (next)) == SET