diff --git a/vm_dump.c b/vm_dump.c
index 933e8db269..67afcff5e4 100644
--- a/vm_dump.c
+++ b/vm_dump.c
@@ -831,7 +831,6 @@ print_machine_register(size_t reg, const char *reg_name, int col_count, int max_
 #else
     ret = snprintf(buf, sizeof(buf), " %3.3s: 0x%08" PRIxSIZE, reg_name, reg);
 #endif
-#undef zx
     if (col_count + ret > max_col) {
 	fputs("\n", stderr);
 	col_count = 0;