diff --git a/src/distributions/base-installer.ts b/src/distributions/base-installer.ts
index b073be8f..46cecfb6 100644
--- a/src/distributions/base-installer.ts
+++ b/src/distributions/base-installer.ts
@@ -324,18 +324,23 @@ export abstract class JavaBase {
   }
 
   protected getJdkCachePath(version: string): string {
+    const toolCache = process.env['RUNNER_TOOL_CACHE'];
+    if (!toolCache) {
+      return '';
+    }
     return path.join(
-      process.env['RUNNER_TOOL_CACHE'] ?? '',
+      toolCache,
       this.toolcacheFolderName,
       this.getToolcacheVersionName(version)
     );
   }
 
   protected getRestoredJdkPath(version: string): string | null {
-    const architecturePath = path.join(
-      this.getJdkCachePath(version),
-      this.architecture
-    );
+    const basePath = this.getJdkCachePath(version);
+    if (!basePath) {
+      return null;
+    }
+    const architecturePath = path.join(basePath, this.architecture);
     return fs.existsSync(architecturePath) &&
       fs.existsSync(`${architecturePath}.complete`)
       ? architecturePath
diff --git a/src/jdk-cache.ts b/src/jdk-cache.ts
index ae305c2e..137eacbc 100644
--- a/src/jdk-cache.ts
+++ b/src/jdk-cache.ts
@@ -99,18 +99,20 @@ export async function saveJdkCaches(): Promise<void> {
 }
 
 export function buildJdkCacheKey(jdk: JdkCache): string {
+  const runnerOs = process.env['RUNNER_OS'] ?? process.platform;
+  const normalizedArchitecture = jdk.architecture.toLowerCase();
   const identity = JSON.stringify({
     keyVersion: JDK_CACHE_KEY_VERSION,
-    runnerOs: process.env['RUNNER_OS'] ?? process.platform,
+    runnerOs,
     platform: process.platform,
     distribution: jdk.distribution.toLowerCase(),
     packageType: jdk.packageType.toLowerCase(),
-    architecture: jdk.architecture.toLowerCase(),
+    architecture: normalizedArchitecture,
     version: jdk.version,
     source: jdk.source
   });
   const digest = createHash('sha256').update(identity).digest('hex');
-  return `setup-java-jdk-v${JDK_CACHE_KEY_VERSION}-${process.env['RUNNER_OS'] ?? process.platform}-${jdk.architecture}-${digest}`;
+  return `setup-java-jdk-v${JDK_CACHE_KEY_VERSION}-${runnerOs}-${normalizedArchitecture}-${digest}`;
 }
 
 function parseJdkCacheState(state: string): JdkCacheState[] {