diff --git a/guppylang/ast_util.py b/guppylang/ast_util.py
index 309496bf..99231473 100644
--- a/guppylang/ast_util.py
+++ b/guppylang/ast_util.py
@@ -343,4 +343,8 @@ def has_empty_body(func_ast: ast.FunctionDef) -> bool:
     if len(func_ast.body) > 1:
         return False
     [n] = func_ast.body
-    return isinstance(n, ast.Expr) and isinstance(n.value, ast.Ellipsis)
+    return (
+        isinstance(n, ast.Expr)
+        and isinstance(n.value, ast.Constant)
+        and n.value.value == Ellipsis
+    )