diff --git a/src/basic/log.h b/src/basic/log.h
index 625be22402..740fdbf617 100644
--- a/src/basic/log.h
+++ b/src/basic/log.h
@@ -74,7 +74,7 @@ int log_get_max_level_realm(LogRealm realm) _pure_;
  */
 
 assert_cc(STRLEN(__FILE__) > STRLEN(RELATIVE_SOURCE_PATH) + 1);
-#define PROJECT_FILE (__FILE__ + STRLEN(RELATIVE_SOURCE_PATH) + 1)
+#define PROJECT_FILE (&__FILE__[STRLEN(RELATIVE_SOURCE_PATH) + 1])
 
 int log_open(void);
 void log_close(void);