diff --git a/src/plugins/debugger/watchutils.cpp b/src/plugins/debugger/watchutils.cpp
index 5693c2c2159adfa034117f184ca3df28b498b724..407ada9cadfbb74c7421917257817a11f5fa1086 100644
--- a/src/plugins/debugger/watchutils.cpp
+++ b/src/plugins/debugger/watchutils.cpp
@@ -136,6 +136,7 @@ bool hasSideEffects(const QString &exp)
     return exp.contains(QLatin1String("-="))
         || exp.contains(QLatin1String("+="))
         || exp.contains(QLatin1String("/="))
+        || exp.contains(QLatin1String("%="))
         || exp.contains(QLatin1String("*="))
         || exp.contains(QLatin1String("&="))
         || exp.contains(QLatin1String("|="))