diff --git a/index.d.ts b/index.d.ts
index bc6ba0b..1f30e63 100644
--- a/index.d.ts
+++ b/index.d.ts
@@ -99,10 +99,10 @@ export default class CacheableLookup {
 	/**
 	 * @see https://nodejs.org/api/dns.html#dns_dns_lookup_hostname_options_callback
 	 */
-	lookup(hostname: string, family: IPFamily, callback: (error: NodeJS.ErrnoException, address: string, family: IPFamily) => void): void;
-	lookup(hostname: string, callback: (error: NodeJS.ErrnoException, address: string, family: IPFamily) => void): void;
-	lookup(hostname: string, options: LookupOptions & {all: true}, callback: (error: NodeJS.ErrnoException, result: ReadonlyArray<EntryObject>) => void): void;
-	lookup(hostname: string, options: LookupOptions, callback: (error: NodeJS.ErrnoException, address: string, family: IPFamily) => void): void;
+	lookup(hostname: string, family: IPFamily, callback: (error: NodeJS.ErrnoException | null, address: string, family: IPFamily) => void): void;
+	lookup(hostname: string, callback: (error: NodeJS.ErrnoException | null, address: string, family: IPFamily) => void): void;
+	lookup(hostname: string, options: LookupOptions & {all: true}, callback: (error: NodeJS.ErrnoException | null, result: ReadonlyArray<EntryObject>) => void): void;
+	lookup(hostname: string, options: LookupOptions, callback: (error: NodeJS.ErrnoException | null, address: string, family: IPFamily) => void): void;
 	/**
 	 * The asynchronous version of `dns.lookup(…)`.
 	 */
diff --git a/index.test-d.ts b/index.test-d.ts
index 17547c9..678c9e2 100644
--- a/index.test-d.ts
+++ b/index.test-d.ts
@@ -37,22 +37,25 @@ import CacheableLookup, {EntryObject} from '.';
 	expectType<ReadonlyArray<EntryObject>>(await cacheable.lookupAsync('localhost', {all: true}));
 
 	cacheable.lookup('localhost', 6, (error, address, family) => {
-		expectType<NodeJS.ErrnoException>(error);
+		expectType<NodeJS.ErrnoException | null>(error);
 		expectType<string>(address);
 		expectType<4 | 6>(family);
 	});
 
 	cacheable.lookup('localhost', {all: false}, (error, address, family) => {
-		expectType<NodeJS.ErrnoException>(error);
+		expectType<NodeJS.ErrnoException | null>(error);
 		expectType<string>(address);
 		expectType<4 | 6>(family);
 	});
 
 	cacheable.lookup('localhost', {all: true}, (error, results) => {
-		expectType<NodeJS.ErrnoException>(error);
+		expectType<NodeJS.ErrnoException | null>(error);
 		expectType<ReadonlyArray<EntryObject>>(results);
 	});
 
+	// @types/node has invalid typings :(
+	// expectType<typeof cacheable.lookup>(lookup);
+
 	expectType<ReadonlyArray<EntryObject>>(await cacheable.query('localhost'));
 	expectType<ReadonlyArray<EntryObject>>(await cacheable.queryAndCache('localhost'));