diff --git a/src/interpreter.c b/src/interpreter.c
index 2b27c01..9d6a5e2 100644
--- a/src/interpreter.c
+++ b/src/interpreter.c
@@ -225,6 +225,9 @@ void addArgsToGroundFunction(GroundFunction* function, GroundValueType type, cha
 };
 
 GroundValueType stringToValueType(char* in) {
+    if (in == NULL) {
+        return ANY;
+    }
     if (strcmp(in, "int") == 0) {
         return INT;
     }
diff --git a/src/types.c b/src/types.c
index 25a03fc..1483cc8 100644
--- a/src/types.c
+++ b/src/types.c
@@ -362,6 +362,10 @@ void printGroundArg(GroundArg* ga) {
             break;
         }
         case TYPEREF: {
+            if (ga->value.refName == NULL) {
+                printf("-any");
+                break;
+            }
             printf("-%s", ga->value.refName);
             break;
         }