diff --git a/include/zephyr/sys/cbprintf_internal.h b/include/zephyr/sys/cbprintf_internal.h
index 5334bef193..ce6e8352de 100644
--- a/include/zephyr/sys/cbprintf_internal.h
+++ b/include/zephyr/sys/cbprintf_internal.h
@@ -382,6 +382,20 @@ do { \
 		 _name##_buf32)))
 #endif
 
+/* When the first argument of Z_CBPRINTF_STATIC_PACKAGE_GENERIC() is a
+ * static memory location, some compiler warns you if you compare the
+ * location against NULL.  ___is_null() is used to kill this warning.
+ *
+ * The warnings would be visible when you built with -save-temps=obj,
+ * our standard debugging tip for macro problems.
+ *
+ * https://github.com/zephyrproject-rtos/zephyr/issues/51528
+ */
+static ALWAYS_INLINE bool ___is_null(void *p)
+{
+	return p == NULL;
+}
+
 /** @brief Statically package a formatted string with arguments.
  *
  * @param buf buffer. If null then only length is calculated.
@@ -430,7 +444,7 @@ do { \
 	Z_CBPRINTF_ON_STACK_ALLOC(_ros_pos_buf, _ros_cnt); \
 	uint8_t *_rws_buffer; \
 	Z_CBPRINTF_ON_STACK_ALLOC(_rws_buffer, 2 * _rws_cnt); \
-	size_t _pmax = (buf != NULL) ? _inlen : INT32_MAX; \
+	size_t _pmax = !___is_null(buf) ? _inlen : INT32_MAX; \
 	int _pkg_len = 0; \
 	int _total_len = 0; \
 	int _pkg_offset = _align_offset; \