diff --git a/src/output.cpp b/src/output.cpp
--- a/src/output.cpp
+++ b/src/output.cpp
@@ -553,6 +553,7 @@
     }
     if (!d->compareModeList(d->modeList, other->d->modeList)) {
         changes << &Output::outputChanged;
+        changes << &Output::modesChanged;
     }
 
     setPreferredModes(other->d->preferredModes);