diff --git a/IPython/core/inputtransformer2.py b/IPython/core/inputtransformer2.py
index 3c992d8..63cf1d7 100644
--- a/IPython/core/inputtransformer2.py
+++ b/IPython/core/inputtransformer2.py
@@ -636,7 +636,7 @@ class TransformerManager:
                 MemoryError, SyntaxWarning):
             return 'invalid', None
         else:
-            if not lines[-1].strip().endswith(':'):
+            if len(lines) > 1 and not lines[-1].strip().endswith(':'):
                 return 'incomplete', find_last_indent(lines)
         return 'complete', None