diff --git a/__tests__/setup-go.test.ts b/__tests__/setup-go.test.ts
index 09d76c0..b99f21b 100644
--- a/__tests__/setup-go.test.ts
+++ b/__tests__/setup-go.test.ts
@@ -471,6 +471,26 @@ describe('setup-go', () => {
     expect(cnSpy).toHaveBeenCalledWith(`::add-path::${expPath}${osm.EOL}`);
   });
 
+  it('finds a rc version of go already in the cache', async () => {
+    inputs['go-version'] = '1.14rc1';
+
+    const toolPath = path.normalize('/cache/go/1.14.0rc.1/x64');
+    findSpy.mockImplementation(() => toolPath);
+    await main.run();
+
+    expect(logSpy).toHaveBeenCalledWith(`Found in cache @ ${toolPath}`);
+  });
+
+  it('finds a rc version in the cache and adds it to the path', async () => {
+    inputs['go-version'] = '1.14rc1';
+    const toolPath = path.normalize('/cache/go/1.14.0.rc.1/x64');
+    findSpy.mockImplementation(() => toolPath);
+    await main.run();
+
+    const expPath = path.join(toolPath, 'bin');
+    expect(cnSpy).toHaveBeenCalledWith(`::add-path::${expPath}${osm.EOL}`);
+  });
+
   it('handles unhandled error and reports error', async () => {
     const errMsg = 'unhandled error message';
     inputs['go-version'] = '1.13.0';
@@ -527,6 +547,51 @@ describe('setup-go', () => {
     expect(cnSpy).toHaveBeenCalledWith(`::add-path::${expPath}${osm.EOL}`);
   });
 
+  it('downloads a rc version not in the cache', async () => {
+    os.platform = 'linux';
+    os.arch = 'x64';
+
+    inputs['go-version'] = '1.14rc1';
+
+    findSpy.mockImplementation(() => '');
+    dlSpy.mockImplementation(() => '/some/temp/path');
+    const toolPath = path.normalize('/cache/go/1.14.0-rc.1/x64');
+    extractTarSpy.mockImplementation(() => '/some/other/temp/path');
+    cacheSpy.mockImplementation(() => toolPath);
+    await main.run();
+
+    const expPath = path.join(toolPath, 'bin');
+
+    expect(dlSpy).toHaveBeenCalled();
+    expect(extractTarSpy).toHaveBeenCalled();
+    expect(cnSpy).toHaveBeenCalledWith(`::add-path::${expPath}${osm.EOL}`);
+  });
+
+  it('downloads a rc version not in the cache (windows)', async () => {
+    os.platform = 'win32';
+    os.arch = 'x64';
+
+    inputs['go-version'] = '1.14rc1';
+    process.env['RUNNER_TEMP'] = 'C:\\temp\\';
+
+    findSpy.mockImplementation(() => '');
+    dlSpy.mockImplementation(() => 'C:\\temp\\some\\path');
+    extractZipSpy.mockImplementation(() => 'C:\\temp\\some\\other\\path');
+
+    const toolPath = path.normalize('C:\\cache\\go\\1.21.0-rc.2\\x64');
+    cacheSpy.mockImplementation(() => toolPath);
+
+    await main.run();
+
+    const expPath = path.win32.join(toolPath, 'bin');
+    expect(dlSpy).toHaveBeenCalledWith(
+      'https://go.dev/dl/go1.14rc1.windows-amd64.zip',
+      'C:\\temp\\go1.14rc1.windows-amd64.zip',
+      undefined
+    );
+    expect(cnSpy).toHaveBeenCalledWith(`::add-path::${expPath}${osm.EOL}`);
+  });
+
   it('does not find a version that does not exist', async () => {
     os.platform = 'linux';
     os.arch = 'x64';
diff --git a/dist/setup/index.js b/dist/setup/index.js
index 6782368..9a1f0b4 100644
--- a/dist/setup/index.js
+++ b/dist/setup/index.js
@@ -42006,8 +42006,12 @@ async function getGo(versionSpec, checkLatest, auth, arch = external_os_default(
     const toolCacheName = customBaseUrl
         ? customToolCacheName(customBaseUrl)
         : 'go';
+    // Convert prerelease specs (1.21rc2) to semver (1.21.0-rc.2).
+    const cacheSpec = /^\d+\.\d+(\.\d+)?(beta|rc)\d+$/.test(versionSpec)
+        ? makeSemver(versionSpec)
+        : versionSpec;
     // check cache
-    const toolPath = find(toolCacheName, versionSpec, arch);
+    const toolPath = find(toolCacheName, cacheSpec, arch);
     // If not found in cache, download
     if (toolPath) {
         core_info(`Found in cache @ ${toolPath}`);
diff --git a/src/installer.ts b/src/installer.ts
index f9c11f9..92a2223 100644
--- a/src/installer.ts
+++ b/src/installer.ts
@@ -123,8 +123,13 @@ export async function getGo(
     ? customToolCacheName(customBaseUrl)
     : 'go';
 
+  // Convert prerelease specs (1.21rc2) to semver (1.21.0-rc.2).
+  const cacheSpec = /^\d+\.\d+(\.\d+)?(beta|rc)\d+$/.test(versionSpec)
+    ? makeSemver(versionSpec)
+    : versionSpec;
+
   // check cache
-  const toolPath = tc.find(toolCacheName, versionSpec, arch);
+  const toolPath = tc.find(toolCacheName, cacheSpec, arch);
   // If not found in cache, download
   if (toolPath) {
     core.info(`Found in cache @ ${toolPath}`);