diff --git a/generic/tclClockFmt.c b/generic/tclClockFmt.c
index 1af0c68..851a78d 100644
--- a/generic/tclClockFmt.c
+++ b/generic/tclClockFmt.c
@@ -95,7 +95,7 @@ _str2wideInt_no(
 }
 
 /* int & Tcl_WideInt overflows may happens here (expected case) */
-#if defined(__GNUC__) || defined(__GNUG__)
+#if (defined(__GNUC__) || defined(__GNUG__)) && !defined(__clang__)
 # pragma GCC optimize("no-trapv")
 #endif
 
@@ -187,7 +187,7 @@ TclAtoWIe(
     return _str2wideInt(out, p, e, sign);
 }
 
-#if defined(__GNUC__) || defined(__GNUG__)
+#if (defined(__GNUC__) || defined(__GNUG__)) && !defined(__clang__)
 # pragma GCC reset_options
 #endif