diff --git a/de.peeeq.wurstscript/src/main/java/de/peeeq/wurstscript/intermediatelang/optimizer/TempMerger.java b/de.peeeq.wurstscript/src/main/java/de/peeeq/wurstscript/intermediatelang/optimizer/TempMerger.java
index f4d982637..ab8ce93ca 100644
--- a/de.peeeq.wurstscript/src/main/java/de/peeeq/wurstscript/intermediatelang/optimizer/TempMerger.java
+++ b/de.peeeq.wurstscript/src/main/java/de/peeeq/wurstscript/intermediatelang/optimizer/TempMerger.java
@@ -402,9 +402,13 @@ private boolean isMergable(ImVar left, ImExpr e) {
          */
         private void invalidateVar(ImVar left) {
             currentValues.remove(left);
+            if (left.isGlobal()) {
+                invalidateGlobals();
+            } else {
+                currentValues.removeAll(readBy.lookup(left));
+            }
         }
 
-
         @Override
         public String toString() {
             ArrayList<ImVar> keys = Lists.newArrayList(currentValues.keySet());