diff --git a/imixs-workflow-core/src/main/java/org/imixs/workflow/ModelManager.java b/imixs-workflow-core/src/main/java/org/imixs/workflow/ModelManager.java
index 5256bfed..aad3a662 100644
--- a/imixs-workflow-core/src/main/java/org/imixs/workflow/ModelManager.java
+++ b/imixs-workflow-core/src/main/java/org/imixs/workflow/ModelManager.java
@@ -90,8 +90,11 @@ public void addModel(BPMNModel model) throws ModelException {
      * Removes a BPMNModel form the local model store
      */
     public void removeModel(String version) {
-        modelStore.remove(version);
-        clearCache();
+        // Test if version exists
+        if (modelStore.containsKey(version)) {
+            modelStore.remove(version);
+            clearCache();
+        }
     }
 
     /**