diff --git a/src/interp.py b/src/interp.py
index 2f0c8a5..c8eb8a4 100644
--- a/src/interp.py
+++ b/src/interp.py
@@ -46,8 +46,7 @@
         compare = args[0]
         if compare.__class__ != Text:
             raise InterpreterError(
-                "Invalid argument type %s, expected Text"
-                % (appendix.__class__.__name__)
+                "Invalid argument type %s, expected Text" % (compare.__class__.__name__)
             )
         return Bool(self.value == compare.value)