diff --git a/src/storage/jani/Assignment.cpp b/src/storage/jani/Assignment.cpp
index cbbd45ba7..e553c710c 100644
--- a/src/storage/jani/Assignment.cpp
+++ b/src/storage/jani/Assignment.cpp
@@ -38,7 +38,7 @@ namespace storm  {
             this->setAssignedExpression(this->getAssignedExpression().substitute(substitution));
         }
         
-        uint64_t Assignment::getLevel() const {
+        int64_t Assignment::getLevel() const {
             return level;
         }
         
diff --git a/src/storage/jani/Assignment.h b/src/storage/jani/Assignment.h
index 7886a5b5b..2da97d3a1 100644
--- a/src/storage/jani/Assignment.h
+++ b/src/storage/jani/Assignment.h
@@ -50,7 +50,7 @@ namespace storm {
             /*!
              * Retrieves the level of the assignment.
              */
-            uint64_t getLevel() const;
+            int64_t getLevel() const;
             
             friend std::ostream& operator<<(std::ostream& stream, Assignment const& assignment);