diff --git a/src/auth.test.ts b/src/auth.test.ts
index 346428f..5a0a39f 100644
--- a/src/auth.test.ts
+++ b/src/auth.test.ts
@@ -31,6 +31,13 @@ describe('Auth', async () => {
         expect(await validateAt(user, await generatePassAt(user + 'a', 1), 1)).toBe(false);
     });
 
+    it('rejects missing signature', async () => {
+        let pass = await generatePassAt(user, 1);
+        // pass is ts:hex-sig, remove the signature
+        pass = pass.substring(0, pass.indexOf(':'));
+        expect(await validateAt(user, pass, 11)).toBe(false);
+    });
+
     it('rejects long signature', async () => {
         let pass = await generatePassAt(user, 1);
         // pass is ts:hex-sig, change the sig length
diff --git a/src/auth.ts b/src/auth.ts
index 894b24a..e898633 100644
--- a/src/auth.ts
+++ b/src/auth.ts
@@ -34,6 +34,9 @@ export async function createAuthWithClock(secret: string, maxAgeSeconds: number,
             const truncatedSignatureLength = 10;
 
             const [ts, sig] = password.split(':');
+            if (!ts || !sig) {
+                return false;
+            }
             const actual = Buffer.from(sig, 'hex');
             if (actual.length !== truncatedSignatureLength) {
                 // timingSafeEqual throws if the buffers are not the same length
@@ -56,4 +59,3 @@ export async function createAuthWithClock(secret: string, maxAgeSeconds: number,
 export async function createAuth(secret: string, maxAgeSeconds: number): Promise<Auth> {
     return await createAuthWithClock(secret, maxAgeSeconds, () => Math.floor(new Date().getTime() / 1000));
 }
-
diff --git a/src/index.ts b/src/index.ts
index de9b84d..0ac87e2 100644
--- a/src/index.ts
+++ b/src/index.ts
@@ -312,7 +312,7 @@ function parseBasicAuth(auth: string): Credentials | ParseError {
 
     const [username, ...rest] = decoded.split(':');
     const password = rest.join(':');
-    if (!password) {
+    if (!username || !password) {
         return {state: 'error', error: error(400, 'invalid auth format')};
     }
     return {state: 'success', user: username, password: password};
diff --git a/tsconfig.json b/tsconfig.json
index 138318c..b3e739e 100644
--- a/tsconfig.json
+++ b/tsconfig.json
@@ -107,7 +107,8 @@
     // "exactOptionalPropertyTypes": true,               /* Interpret optional property types as written, rather than adding 'undefined'. */
     // "noImplicitReturns": true,                        /* Enable error reporting for codepaths that do not explicitly return in a function. */
     // "noFallthroughCasesInSwitch": true,               /* Enable error reporting for fallthrough cases in switch statements. */
-    // "noUncheckedIndexedAccess": true,                 /* Include 'undefined' in index signature results */
+    /* Include 'undefined' in index signature results */
+    "noUncheckedIndexedAccess": true,
     // "noImplicitOverride": true,                       /* Ensure overriding members in derived classes are marked with an override modifier. */
     // "noPropertyAccessFromIndexSignature": true,       /* Enforces using indexed accessors for keys declared using an indexed type */
     // "allowUnusedLabels": true,                        /* Disable error reporting for unused labels. */