diff --git a/src/main.cpp b/src/main.cpp
index 9b12bda..80b7e6a 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -2073,6 +2073,7 @@ Literal exec(vector<Instruction> in, bool executingFunction) {
                 break;
         }
     }
+    if (executingFunction) error("Reached end of function and no value returned");
     Literal retLiteral;
     return retLiteral;
 }