diff --git a/src/util.js b/src/util.js
index 61bebe5..5261544 100644
--- a/src/util.js
+++ b/src/util.js
@@ -241,16 +241,16 @@ function verifyGpgSignature(file, opts = {}) {
   // binary transform (also no agent) to turn the committed .asc key into the
   // binary keyring gpgv wants.
   //
-  // gpgv treats a --keyring path with NO slash as a name inside ~/.gnupg. On
-  // Windows the paths are backslash-separated (C:\...), which the MSYS gpgv
-  // sees as slash-less and mis-resolves. Convert to forward slashes (valid on
-  // Windows, and gpgv then uses the path literally).
   const fwd = (p) => p.replace(/\\/g, '/');
+  // gpgv reads a leading `scheme:` in --keyring as a resource URL, so a Windows
+  // C:/... path fails with "invalid key resource URL". The gnupg-ring: prefix
+  // forces it to take the rest as a literal filename (no-op on POSIX paths).
+  const keyringArg = `gnupg-ring:${fwd(keyringFile)}`;
   return download(sigUrl, sigFile, headers)
     .catch(err => { throw sigError(`could not fetch signature ${sigUrl}: ${err.message}`); })
     .then(() => runCommand('gpg', ['--batch', '--no-tty', '--yes', '--dearmor', '-o', keyringFile, keyPath], undefined, undefined, true)
       .catch(() => { throw sigError(`failed to prepare public key ${keyPath}`); }))
-    .then(() => runCommand('gpgv', ['--keyring', fwd(keyringFile), fwd(sigFile), fwd(file)], undefined, undefined, true)
+    .then(() => runCommand('gpgv', ['--keyring', keyringArg, fwd(sigFile), fwd(file)], undefined, undefined, true)
       .catch(() => { throw sigError(`GPG signature verification failed for ${file}`); }))
     .then(() => { log(`verified GPG signature for ${file}`); cleanup(); })
     .catch(err => { cleanup(); throw err; });
diff --git a/test/gpg-verify.test.js b/test/gpg-verify.test.js
index 98a0a92..49eda3e 100644
--- a/test/gpg-verify.test.js
+++ b/test/gpg-verify.test.js
@@ -114,6 +114,18 @@ describe('verifyGpgSignature (e2e with real gpg)', { skip: !gpgInstalled() }, ()
     await verifyGpgSignature(bin, { binaryUrl, keyPath });
   });
 
+  it('resolves when the keyring lives under a path with a colon (drive-letter shape)', async () => {
+    // A `<letter>:` prefix made gpgv reject the keyring as an invalid resource
+    // URL on Windows. A `C:` dir reproduces it on any platform.
+    const colonDir = path.join(work, 'C:');
+    fs.mkdirSync(colonDir, { recursive: true });
+    const bin = path.join(colonDir, 'node-bin-colon');
+    fs.writeFileSync(bin, 'colon path bytes');
+    sign(bin);
+    const binaryUrl = `http://${sigHost}/criblio/js2bin/releases/download/v1.0.9/node-bin-colon`;
+    await verifyGpgSignature(bin, { binaryUrl, keyPath });
+  });
+
   it('uses an explicit sigUrl when provided', async () => {
     const bin = path.join(work, 'node-bin-explicit');
     fs.writeFileSync(bin, 'explicit sig url bytes');