diff --git a/src/mfm/language.ts b/src/mfm/language.ts
index 8f35d443dc..bfb0f249c2 100644
--- a/src/mfm/language.ts
+++ b/src/mfm/language.ts
@@ -142,7 +142,7 @@ export const mfmLanguage = P.createLanguage({
 	},
 	hashtag: () => P((input, i) => {
 		const text = input.substr(i);
-		const match = text.match(/^#([^\s\.,!\?'"#:]+)/i);
+		const match = text.match(/^#([^\s\.,!\?'"#:\/]+)/i);
 		if (!match) return P.makeFailure(i, 'not a hashtag');
 		let hashtag = match[1];
 		hashtag = removeOrphanedBrackets(hashtag);
diff --git a/test/mfm.ts b/test/mfm.ts
index 8d5496a5f8..7db94b45e1 100644
--- a/test/mfm.ts
+++ b/test/mfm.ts
@@ -611,6 +611,14 @@ describe('MFM', () => {
 					text('(#123)'),
 				]);
 			});
+
+			it('ignore slash', () => {
+				const tokens = parse('#foo/bar');
+				assert.deepStrictEqual(tokens, [
+					leaf('hashtag', { hashtag: 'foo' }),
+					text('/bar'),
+				]);
+			});
 		});
 
 		describe('quote', () => {