diff --git a/pattern/text/tree.py b/pattern/text/tree.py
index 11fee24f..29563fbb 100644
--- a/pattern/text/tree.py
+++ b/pattern/text/tree.py
@@ -686,7 +686,7 @@ def anchors(self):
 
     @property
     def is_question(self):
-        return len(self) > 0 and str(self[-1]) == "?"
+        return len(self) > 0 and str(self.string[-1]) == "?"
     @property
     def is_exclamation(self):
         return len(self) > 0 and str(self[-1]) == "!"
@@ -1712,4 +1712,4 @@ def outline(column, fill=1, padding=3, align="left"):
         del columns[6] 
     # Create a string with one row (i.e., one token) per line.
     return "\n".join(["".join([x[i] for x in columns]) for i in range(len(columns[0]))])
-    
\ No newline at end of file
+