diff --git a/packages/vinext/src/build/prerender-paths.ts b/packages/vinext/src/build/prerender-paths.ts
index 13897ef2a..f915611d7 100644
--- a/packages/vinext/src/build/prerender-paths.ts
+++ b/packages/vinext/src/build/prerender-paths.ts
@@ -185,7 +185,12 @@ function validateDiscoveredParams(
 
 function validatePagesStaticPathsEntry(entry: StaticPathsEntry, pattern: string): StaticPathsEntry {
   if (typeof entry === "string") {
-    if (entry.includes("?") || entry.includes("#")) {
+    if (
+      !entry.startsWith("/") ||
+      entry.includes("//") ||
+      entry.includes("?") ||
+      entry.includes("#")
+    ) {
       throw new Error(
         `The provided path \`${entry}\` from getStaticPaths does not match the route pattern \`${pattern}\`.`,
       );
@@ -381,10 +386,12 @@ async function collectPagesPaths(options: {
         const validatedItem = validatePagesStaticPathsEntry(item, route.pattern);
         let itemToNormalize = validatedItem;
         let locale = options.i18n?.defaultLocale;
+        let explicitLocalePrefix: string | undefined;
         if (options.i18n && typeof validatedItem === "string") {
           const localeInfo = extractPagesStaticPathLocale(validatedItem, options.i18n);
           itemToNormalize = localeInfo.url;
           locale = localeInfo.locale;
+          explicitLocalePrefix = localeInfo.explicitLocalePrefix;
         } else if (
           options.i18n &&
           validatedItem &&
@@ -404,7 +411,11 @@ async function collectPagesPaths(options: {
           throw new Error(normalized.error);
         }
         const pathname = buildUrlFromParams(route.pattern, normalized.params);
-        addPath(paths, seen, localizePagesPath(pathname, locale, options.i18n));
+        addPath(
+          paths,
+          seen,
+          localizePagesPath(pathname, locale, options.i18n, explicitLocalePrefix),
+        );
       }
     } catch (error) {
       throwDiscoveryFailure(route.pattern, error);
@@ -418,7 +429,11 @@ function localizePagesPath(
   pathname: string,
   locale: string | undefined,
   i18n: ResolvedNextConfig["i18n"],
+  explicitLocalePrefix?: string,
 ): string {
+  if (explicitLocalePrefix) {
+    return pathname === "/" ? `/${explicitLocalePrefix}` : `/${explicitLocalePrefix}${pathname}`;
+  }
   if (!i18n || !locale || locale === i18n.defaultLocale) return pathname;
   return pathname === "/" ? `/${locale}` : `/${locale}${pathname}`;
 }
@@ -426,7 +441,7 @@ function localizePagesPath(
 function extractPagesStaticPathLocale(
   url: string,
   i18n: NonNullable<ResolvedNextConfig["i18n"]>,
-): { locale: string; url: string } {
+): { explicitLocalePrefix?: string; locale: string; url: string } {
   const queryIndex = url.indexOf("?");
   const pathname = queryIndex === -1 ? url : url.slice(0, queryIndex);
   const query = queryIndex === -1 ? "" : url.slice(queryIndex);
@@ -437,7 +452,7 @@ function extractPagesStaticPathLocale(
       : undefined;
   if (!locale) return extractLocaleFromUrl(url, i18n);
   const rest = `/${parts.slice(1).join("/")}`;
-  return { locale, url: `${rest || "/"}${query}` };
+  return { explicitLocalePrefix: parts[0], locale, url: `${rest || "/"}${query}` };
 }
 
 async function collectAppPaths(options: {
@@ -473,13 +488,16 @@ async function collectAppPaths(options: {
           if (!Array.isArray(value)) {
             throw new Error(`generateStaticParams must return an array for ${pattern}.`);
           }
-          return value.map((entry) =>
-            validateDiscoveredParams(
+          return value.map((entry) => {
+            if (!entry || typeof entry !== "object" || Array.isArray(entry)) {
+              throw new Error(`generateStaticParams must return parameter objects for ${pattern}.`);
+            }
+            return validateDiscoveredParams(
               { ...params, ...(entry as Record<string, unknown>) },
               pattern,
               "generateStaticParams",
-            ),
-          );
+            );
+          });
         })();
         void request.catch(() => staticParamsCache.delete(cacheKey));
         staticParamsCache.set(cacheKey, request);
diff --git a/packages/vinext/src/server/app-prerender-static-params.ts b/packages/vinext/src/server/app-prerender-static-params.ts
index 62e444a20..3cef23b80 100644
--- a/packages/vinext/src/server/app-prerender-static-params.ts
+++ b/packages/vinext/src/server/app-prerender-static-params.ts
@@ -35,7 +35,9 @@ function isLazyStaticParamsSource(value: unknown): value is LazyStaticParamsSour
 }
 
 function isRootParams(value: unknown): value is RootParams {
-  return isUnknownRecord(value);
+  if (!isUnknownRecord(value)) return false;
+  const prototype = Object.getPrototypeOf(value);
+  return prototype === Object.prototype || prototype === null;
 }
 
 /**
diff --git a/tests/app-prerender-static-params.test.ts b/tests/app-prerender-static-params.test.ts
index 0db8e7976..66be2d5ce 100644
--- a/tests/app-prerender-static-params.test.ts
+++ b/tests/app-prerender-static-params.test.ts
@@ -82,6 +82,11 @@ describe("createAppPrerenderStaticParamsResolver", () => {
       await expect(nonObjectEntry!({ params: {} })).rejects.toThrow(
         "generateStaticParams must return an array of objects",
       );
+
+      const nonPlainEntry = createAppPrerenderStaticParamsResolver([() => [new Date(0)]]);
+      await expect(nonPlainEntry!({ params: {} })).rejects.toThrow(
+        "generateStaticParams must return an array of objects",
+      );
     } finally {
       if (previous === undefined) delete process.env.__VINEXT_PRERENDER_PATH_DISCOVERY;
       else process.env.__VINEXT_PRERENDER_PATH_DISCOVERY = previous;
diff --git a/tests/prerender-paths.test.ts b/tests/prerender-paths.test.ts
index b1bc41e2e..5396313e5 100644
--- a/tests/prerender-paths.test.ts
+++ b/tests/prerender-paths.test.ts
@@ -699,6 +699,7 @@ describe("prerender path manifest", () => {
             { params: { slug: "bonjour" }, locale: "fr" },
             "/fr/posts/string-fr",
             "/FR/posts/string-fr-upper",
+            "/en/posts/string-en-explicit",
             "/posts/string-en",
           ],
         });
@@ -729,7 +730,8 @@ describe("prerender path manifest", () => {
       "/posts/hello",
       "/fr/posts/bonjour",
       "/fr/posts/string-fr",
-      "/fr/posts/string-fr-upper",
+      "/FR/posts/string-fr-upper",
+      "/en/posts/string-en-explicit",
       "/posts/string-en",
     ]);
     expect(manifest?.pagesPaths).toEqual(manifest?.paths);
@@ -743,7 +745,8 @@ describe("prerender path manifest", () => {
       "/docs/posts/hello/",
       "/docs/fr/posts/bonjour/",
       "/docs/fr/posts/string-fr/",
-      "/docs/fr/posts/string-fr-upper/",
+      "/docs/FR/posts/string-fr-upper/",
+      "/docs/en/posts/string-en-explicit/",
       "/docs/posts/string-en/",
     ]);
   });
@@ -802,6 +805,8 @@ describe("prerender path manifest", () => {
     ["an array dynamic param", "/posts/[slug].tsx", { params: { slug: ["a", "b"] } }],
     ["a scalar catch-all param", "/docs/[...parts].tsx", { params: { parts: "a" } }],
     ["a query-bearing string path", "/posts/[slug].tsx", "/posts/query?x=1"],
+    ["a relative string path", "/posts/[slug].tsx", "posts/x"],
+    ["a double-slash string path", "/posts/[slug].tsx", "/posts//x"],
   ])("fails path discovery for getStaticPaths entry with %s", async (_name, file, entry) => {
     writeFile("package.json", JSON.stringify({ type: "module" }));
     writeFile("dist/server/BUILD_ID", "build-a\n");