diff --git a/src/testRunner/externalCompileRunner.ts b/src/testRunner/externalCompileRunner.ts
index 33d8c15a31..5b59256256 100644
--- a/src/testRunner/externalCompileRunner.ts
+++ b/src/testRunner/externalCompileRunner.ts
@@ -53,7 +53,7 @@ abstract class ExternalCompileRunnerBase extends RunnerBase {
                     if (reset.status !== 0) throw new Error(`git reset for ${directoryName} failed: ${reset.stderr.toString()}`);
                     const clean = cp.spawnSync("git", ["clean", "-f"], { cwd: submoduleDir, timeout, shell: true, stdio });
                     if (clean.status !== 0) throw new Error(`git clean for ${directoryName} failed: ${clean.stderr.toString()}`);
-                    const update = cp.spawnSync("git", ["submodule", "update", "--remote", "."], { cwd: submoduleDir, timeout, shell: true, stdio });
+                    const update = cp.spawnSync("git", ["submodule", "update", "--remote", ".", "--init"], { cwd: submoduleDir, timeout, shell: true, stdio });
                     if (update.status !== 0) throw new Error(`git submodule update for ${directoryName} failed: ${update.stderr.toString()}`);
 
                     const config = JSON.parse(fs.readFileSync(path.join(cwd, "test.json"), { encoding: "utf8" })) as UserConfig;