diff --git a/gnu/usr.bin/gdb/kgdb/trgt_amd64.c b/gnu/usr.bin/gdb/kgdb/trgt_amd64.c
index 9b83fd3dd3f3..c3596fb14bd1 100644
--- a/gnu/usr.bin/gdb/kgdb/trgt_amd64.c
+++ b/gnu/usr.bin/gdb/kgdb/trgt_amd64.c
@@ -150,12 +150,15 @@ kgdb_trgt_trapframe_prev_register(struct frame_info *next_frame,
 	*lvalp = not_lval;
 	*realnump = -1;
 
+	cache = kgdb_trgt_frame_cache(next_frame, this_cache);
+	if (cache->pc == 0)
+		return;
+
 	ofs = (regnum >= AMD64_RAX_REGNUM && regnum <= AMD64_EFLAGS_REGNUM + 2)
 	    ? kgdb_trgt_frame_offset[regnum] : -1;
 	if (ofs == -1)
 		return;
 
-	cache = kgdb_trgt_frame_cache(next_frame, this_cache);
 	*addrp = cache->sp + ofs;
 	*lvalp = lval_memory;
 	target_read_memory(*addrp, valuep, regsz);
@@ -174,11 +177,14 @@ kgdb_trgt_trapframe_sniffer(struct frame_info *next_frame)
 	CORE_ADDR pc;
 
 	pc = frame_pc_unwind(next_frame);
+	if (pc == 0)
+		return (&kgdb_trgt_trapframe_unwind);
 	pname = NULL;
 	find_pc_partial_function(pc, &pname, NULL, NULL);
 	if (pname == NULL)
 		return (NULL);
-	if (strcmp(pname, "calltrap") == 0)
+	if (strcmp(pname, "calltrap") == 0 ||
+	    (pname[0] == 'X' && pname[1] != '_'))
 		return (&kgdb_trgt_trapframe_unwind);
 	/* printf("%s: %lx =%s\n", __func__, pc, pname); */
 	return (NULL);