diff --git a/flit_core/flit_core/common.py b/flit_core/flit_core/common.py
index 6625224b..9794c170 100644
--- a/flit_core/flit_core/common.py
+++ b/flit_core/flit_core/common.py
@@ -157,10 +157,10 @@ def get_docstring_and_version_via_ast(target):
                         and target.id == "__version__"
                         for target in child.targets
                     )
-                    and isinstance(child.value, ast.Str)
+                    and isinstance(child.value, ast.Constant)
             )
             if is_version_str:
-                version = child.value.s
+                version = child.value.value
                 break
     return ast.get_docstring(node), version