diff --git a/subsys/testsuite/ztest/include/zephyr/ztest_assert.h b/subsys/testsuite/ztest/include/zephyr/ztest_assert.h
index 0773d3abccd..482f70e5027 100644
--- a/subsys/testsuite/ztest/include/zephyr/ztest_assert.h
+++ b/subsys/testsuite/ztest/include/zephyr/ztest_assert.h
@@ -132,8 +132,10 @@ static inline bool z_zassume(bool cond, const char *default_msg, const char *fil
  */
 #define zassert(cond, default_msg, msg, ...)                                                       \
 	do {                                                                                       \
-		bool _ret = z_zassert(cond, msg ? ("(" default_msg ")") : (default_msg), __FILE__, \
-				      __LINE__, __func__, msg ? msg : "", ##__VA_ARGS__);          \
+		bool _msg = (msg != NULL);                                                         \
+		bool _ret = z_zassert(cond, _msg ? ("(" default_msg ")") : (default_msg), __FILE__,\
+				      __LINE__, __func__, _msg ? msg : "", ##__VA_ARGS__);         \
+		(void)_msg;                                                                        \
 		if (!_ret) {                                                                       \
 			/* If kernel but without multithreading return. */                         \
 			COND_CODE_1(KERNEL, (COND_CODE_1(CONFIG_MULTITHREADING, (), (return;))),   \
@@ -161,8 +163,10 @@ static inline bool z_zassume(bool cond, const char *default_msg, const char *fil
  */
 #define zassume(cond, default_msg, msg, ...)                                                       \
 	do {                                                                                       \
-		bool _ret = z_zassume(cond, msg ? ("(" default_msg ")") : (default_msg), __FILE__, \
-				      __LINE__, __func__, msg ? msg : "", ##__VA_ARGS__);          \
+		bool _msg = (msg != NULL);                                                         \
+		bool _ret = z_zassume(cond, _msg ? ("(" default_msg ")") : (default_msg), __FILE__,\
+				      __LINE__, __func__, _msg ? msg : "", ##__VA_ARGS__);         \
+		(void)_msg;                                                                        \
 		if (!_ret) {                                                                       \
 			/* If kernel but without multithreading return. */                         \
 			COND_CODE_1(KERNEL, (COND_CODE_1(CONFIG_MULTITHREADING, (), (return;))),   \