diff --git a/core/wasm_shims/tooldata/tooldata_probe_main.cc b/core/wasm_shims/tooldata/tooldata_probe_main.cc
index d5a61b4..4d65406 100644
--- a/core/wasm_shims/tooldata/tooldata_probe_main.cc
+++ b/core/wasm_shims/tooldata/tooldata_probe_main.cc
@@ -203,6 +203,19 @@ int main() {
     if (separator == std::string::npos || missing_db_program_with_arg[separator] != 0) {
         return 56;
     }
+    char missing_db_program_with_args[] = "/tmp/cnc_tooldata_probe_missing_db_program alpha beta";
+    if (tooldata_db_init(missing_db_program_with_args, 0) != -1) {
+        return 83;
+    }
+    // LinuxCNC src/emc/tooldata/tooldata_db.cc tokenizes progname_plus_args
+    // in place with strtok_r() before checking whether argv[0] is executable.
+    if (missing_db_program_with_args[42] != 0 ||
+        missing_db_program_with_args[48] != 0 ||
+        std::strcmp(missing_db_program_with_args, "/tmp/cnc_tooldata_probe_missing_db_program") != 0 ||
+        std::strcmp(missing_db_program_with_args + 43, "alpha") != 0 ||
+        std::strcmp(missing_db_program_with_args + 49, "beta") != 0) {
+        return 84;
+    }
     std::string missing_db_program_string = make_temp_path("cnc_tooldata_probe_missing_db_program");
     std::vector<char> missing_db_program(
         missing_db_program_string.begin(),