diff --git a/sw/device/lib/testing/test_coverage.h b/sw/device/lib/testing/test_coverage.h
index 4a0da29..1352df7 100644
--- a/sw/device/lib/testing/test_coverage.h
+++ b/sw/device/lib/testing/test_coverage.h
@@ -2,6 +2,9 @@
 // Licensed under the Apache License, Version 2.0, see LICENSE for details.
 // SPDX-License-Identifier: Apache-2.0
 
+#ifndef OPENTITAN_SW_DEVICE_LIB_TESTING_TEST_COVERAGE_H_
+#define OPENTITAN_SW_DEVICE_LIB_TESTING_TEST_COVERAGE_H_
+
 /**
  * Sends the LLVM profile buffer along with its length and CRC32.
  *
@@ -10,3 +13,5 @@
  * reports.
  */
 void test_coverage_send_buffer(void);
+
+#endif  // OPENTITAN_SW_DEVICE_LIB_TESTING_TEST_COVERAGE_H_