diff --git a/packages/backend/src/core/UtilityService.ts b/packages/backend/src/core/UtilityService.ts
index 5209cf7a3d..f8d04c0592 100644
--- a/packages/backend/src/core/UtilityService.ts
+++ b/packages/backend/src/core/UtilityService.ts
@@ -116,13 +116,22 @@ export class UtilityService {
 
 	@bindThis
 	public toPuny(host: string): string {
-		return domainToASCII(host.toLowerCase());
+		// domainToASCII will return an empty string if we give it a
+		// string like `name:123`, but `host` may well be in that form
+		// (e.g. when testing locally, you'll get `localhost:3000`); split
+		// the port off, and add it back later
+		const hostParts = host.toLowerCase().match(/^(.+?)(:.+)?$/);
+		if (!hostParts) return '';
+		const hostname = hostParts[1];
+		const port = hostParts[2] ?? '';
+
+		return domainToASCII(hostname) + port;
 	}
 
 	@bindThis
 	public toPunyNullable(host: string | null | undefined): string | null {
 		if (host == null) return null;
-		return domainToASCII(host.toLowerCase());
+		return this.toPuny(host);
 	}
 
 	@bindThis
diff --git a/packages/backend/src/server/ActivityPubServerService.ts b/packages/backend/src/server/ActivityPubServerService.ts
index 95ee78d660..41beadb56d 100644
--- a/packages/backend/src/server/ActivityPubServerService.ts
+++ b/packages/backend/src/server/ActivityPubServerService.ts
@@ -179,7 +179,7 @@ export class ActivityPubServerService {
 			 this is also inspired by FireFish's `checkFetch`
 		*/
 
-		let signature;
+		let signature: httpSignature.IParsedSignature;
 
 		try {
 			signature = httpSignature.parseRequest(request.raw, {
@@ -232,14 +232,37 @@ export class ActivityPubServerService {
 			return `${logPrefix} signer is suspended: refuse`;
 		}
 
-		let httpSignatureValidated = httpSignature.verifySignature(signature, authUser.key.keyPem);
+		// some fedi implementations include the query (`?foo=bar`) in the
+		// signature, some don't, so we have to handle both cases
+		function verifyWithOrWithoutQuery() {
+			const httpSignatureValidated = httpSignature.verifySignature(signature, authUser!.key!.keyPem);
+			if (httpSignatureValidated) return true;
+
+			const requestUrl = new URL(`http://whatever${request.raw.url}`);
+			if (! requestUrl.search) return false;
+
+			// verification failed, the request URL contained a query, let's try without
+			const semiRawRequest = request.raw;
+			semiRawRequest.url = requestUrl.pathname;
+
+			// no need for try/catch, if the original request parsed, this
+			// one will, too
+			const signatureWithoutQuery = httpSignature.parseRequest(semiRawRequest, {
+				headers: ['(request-target)', 'host', 'date'],
+				authorizationHeaderName: 'signature',
+			});
+
+			return httpSignature.verifySignature(signatureWithoutQuery, authUser!.key!.keyPem);
+		}
+
+		let httpSignatureValidated = verifyWithOrWithoutQuery();
 
 		// maybe they changed their key? refetch it
 		// TODO rate-limit this using lastFetchedAt
 		if (!httpSignatureValidated) {
 			authUser.key = await this.apDbResolverService.refetchPublicKeyForApId(authUser.user);
 			if (authUser.key != null) {
-				httpSignatureValidated = httpSignature.verifySignature(signature, authUser.key.keyPem);
+				httpSignatureValidated = verifyWithOrWithoutQuery();
 			}
 		}
 
diff --git a/packages/backend/src/server/api/mastodon/endpoints/instance.ts b/packages/backend/src/server/api/mastodon/endpoints/instance.ts
index 0e363446a4..a168339ac6 100644
--- a/packages/backend/src/server/api/mastodon/endpoints/instance.ts
+++ b/packages/backend/src/server/api/mastodon/endpoints/instance.ts
@@ -39,7 +39,7 @@ export class ApiInstanceMastodon {
 
 			const instance = data.data;
 			const response: MastodonEntity.Instance = {
-				uri: this.config.url,
+				uri: this.config.host,
 				title: this.meta.name || 'Sharkey',
 				description: this.meta.description || 'This is a vanilla Sharkey Instance. It doesn\'t seem to have a description.',
 				email: instance.email || '',
diff --git a/packages/backend/test/unit/UtilityService.ts b/packages/backend/test/unit/UtilityService.ts
index d86e794f2f..cb010ff1f9 100644
--- a/packages/backend/test/unit/UtilityService.ts
+++ b/packages/backend/test/unit/UtilityService.ts
@@ -22,6 +22,12 @@ describe('UtilityService', () => {
 		test('japanese', () => {
 			assert.equal(utilityService.punyHost('http://www.新聞.com'), 'www.xn--efvv70d.com');
 		});
+		test('simple, with port', () => {
+			assert.equal(utilityService.punyHost('http://www.foo.com:3000'), 'www.foo.com:3000');
+		});
+		test('japanese, with port', () => {
+			assert.equal(utilityService.punyHost('http://www.新聞.com:3000'), 'www.xn--efvv70d.com:3000');
+		});
 	});
 
 	describe('punyHostPSLDomain', () => {
@@ -31,6 +37,12 @@ describe('UtilityService', () => {
 		test('japanese', () => {
 			assert.equal(utilityService.punyHostPSLDomain('http://www.新聞.com'), 'xn--efvv70d.com');
 		});
+		test('simple, with port', () => {
+			assert.equal(utilityService.punyHostPSLDomain('http://www.foo.com:3000'), 'foo.com:3000');
+		});
+		test('japanese, with port', () => {
+			assert.equal(utilityService.punyHostPSLDomain('http://www.新聞.com:3000'), 'xn--efvv70d.com:3000');
+		});
 		test('lower', () => {
 			assert.equal(utilityService.punyHostPSLDomain('http://foo.github.io'), 'foo.github.io');
 			assert.equal(utilityService.punyHostPSLDomain('http://foo.bar.github.io'), 'bar.github.io');
@@ -40,4 +52,13 @@ describe('UtilityService', () => {
 			assert.equal(utilityService.punyHostPSLDomain('http://foo.bar.masto.host'), 'bar.masto.host');
 		});
 	});
+
+	describe('toPuny', () => {
+		test('without port ', () => {
+			assert.equal(utilityService.toPuny('www.foo.com'), 'www.foo.com');
+		});
+		test('with port ', () => {
+			assert.equal(utilityService.toPuny('www.foo.com:3000'), 'www.foo.com:3000');
+		});
+	});
 });