1 files changed, 3 insertions, 1 deletions

diff --git a/mfd/prog.c b/mfd/prog.c
index 17c2464b..a2671db8 100644
--- a/mfd/prog.c
+++ b/mfd/prog.c
@@ -490,7 +490,9 @@ runtime_stack_trace(eval_environ_t env)
                 prog_counter_t pc = (prog_counter_t)env->dataseg[base + 2] - 1;
                 char *name;
                 struct locus *ploc = NULL, loc;
-                
+
+                if (pc < 2)
+                        break; /*FIXME*/
                 if (prog[pc-2] == instr_funcall) {
                         name = (char*)(env->dataseg + (size_t) prog[pc-1]);
                         pc -= 2;