diff --git a/src/fetch/index.t-test.ts b/src/fetch/index.t-test.ts
index 49e4e66..a2319a2 100644
--- a/src/fetch/index.t-test.ts
+++ b/src/fetch/index.t-test.ts
@@ -128,4 +128,13 @@ import JSONT from "../json";
       headers: { Cookie: "a=b" },
     });
   })();
+
+  (async () => {
+    // basePathの最後にも/があるのでhttps://example.com/api//usersとなってしまうが、ノーマライズされるので問題ない
+    const basePath = "https://example.com/api/";
+    const f = fetch as FetchT<typeof basePath, Spec>;
+    await f(`${basePath}/users`, {
+      headers: { Cookie: "a=b" },
+    });
+  })();
 }
diff --git a/src/fetch/index.ts b/src/fetch/index.ts
index 320f169..0d63816 100644
--- a/src/fetch/index.ts
+++ b/src/fetch/index.ts
@@ -36,9 +36,9 @@ type FetchT<UrlPrefix extends UrlPrefixPattern, E extends ApiEndpoints> = <
   Input extends
     | `${ToUrlParamPattern<UrlPrefix>}${ToUrlParamPattern<keyof E & string>}`
     | `${ToUrlParamPattern<UrlPrefix>}${ToUrlParamPattern<keyof E & string>}?${string}`,
-  InputPath extends ParseURL<
-    Replace<NormalizePath<Input>, NormalizePath<UrlPrefix>, "">
-  >["path"],
+  InputPath extends NormalizePath<
+    ParseURL<Replace<Input, UrlPrefix, "">>["path"]
+  >,
   CandidatePaths extends MatchedPatterns<InputPath, keyof E & string>,
   InputMethod extends CaseInsensitiveMethod = "get",
   M extends Method = Lowercase<InputMethod>,