diff --git a/core/wasm_shims/tooldata/tooldata_probe_main.cc b/core/wasm_shims/tooldata/tooldata_probe_main.cc
index 81600c7..9c8da76 100644
--- a/core/wasm_shims/tooldata/tooldata_probe_main.cc
+++ b/core/wasm_shims/tooldata/tooldata_probe_main.cc
@@ -383,6 +383,16 @@ int main() {
         reloaded.offset.tran.z != 3.5 || reloaded.diameter != 8.0) {
         return 14;
     }
+    tooldata_last_index_set(12);
+    tooldata_reset();
+    // LinuxCNC src/emc/tooldata/tooldata_mmap.cc clears table entries in
+    // tooldata_reset() without changing the mmap header last_index.
+    if (tooldata_last_index_get() != 12) {
+        return 78;
+    }
+    if (tooldata_find_index_for_tool(7) != -1) {
+        return 79;
+    }
 
     tooldata_init(false);
     std::string nonrandom_path_template = make_temp_path("cnc_tooldata_nonrandom_probe_XXXXXX");