diff --git a/mythril/laser/ethereum/instructions.py b/mythril/laser/ethereum/instructions.py
index 3601eb4c..9a0344a0 100644
--- a/mythril/laser/ethereum/instructions.py
+++ b/mythril/laser/ethereum/instructions.py
@@ -808,6 +808,8 @@ class Instruction:
             state.stack.pop(),
             state.stack.pop(),
         )
+        concrete_size = None
+        concrete_return_offset = None
 
         try:
             concrete_memory_offset = helper.get_concrete_int(memory_offset)