diff --git a/core/wasm_shims/tooldata/tooldata_probe_main.cc b/core/wasm_shims/tooldata/tooldata_probe_main.cc
index 3e36a66..33b630c 100644
--- a/core/wasm_shims/tooldata/tooldata_probe_main.cc
+++ b/core/wasm_shims/tooldata/tooldata_probe_main.cc
@@ -113,6 +113,42 @@ int main() {
         return 69;
     }
 
+    const pid_t random_t0_child = fork();
+    if (random_t0_child < 0) {
+        return 70;
+    }
+    if (random_t0_child == 0) {
+        if (tool_mmap_creator(nullptr, 1) != 0) {
+            _exit(71);
+        }
+        tooldata_reset();
+        CANON_TOOL_TABLE spindle_t0 = tooldata_entry_init();
+        spindle_t0.toolno = 0;
+        spindle_t0.pocketno = 0;
+        if (tooldata_put(spindle_t0, 0) == IDX_FAIL) {
+            _exit(72);
+        }
+        CANON_TOOL_TABLE random_t0 = tooldata_entry_init();
+        random_t0.toolno = 0;
+        random_t0.pocketno = 15;
+        if (tooldata_put(random_t0, 15) == IDX_FAIL) {
+            _exit(73);
+        }
+        // LinuxCNC src/emc/tooldata/tooldata_mmap.cc continues past pocket 0
+        // while scanning random toolchanger entries, so a nonzero T0 pocket wins.
+        if (tooldata_find_index_for_tool(0) != 15) {
+            _exit(74);
+        }
+        _exit(0);
+    }
+    int random_t0_status = 0;
+    if (waitpid(random_t0_child, &random_t0_status, 0) != random_t0_child) {
+        return 75;
+    }
+    if (!WIFEXITED(random_t0_status) || WEXITSTATUS(random_t0_status) != 0) {
+        return 76;
+    }
+
     if (tool_mmap_user() != -1) {
         return 25;
     }