diff --git a/src/parse/parser.ts b/src/parse/parser.ts
index 528280fe..fb1453b4 100644
--- a/src/parse/parser.ts
+++ b/src/parse/parser.ts
@@ -529,7 +529,11 @@ export class Parser {
     }
 
     if (this.indent >= map.indent) {
-      const atNextItem = !this.onKeyLine && this.indent === map.indent && it.sep
+      const atNextItem =
+        !this.onKeyLine &&
+        this.indent === map.indent &&
+        it.sep &&
+        this.type !== 'seq-item-ind'
 
       // For empty nodes, assign newline-separated not indented empty tokens to following node
       let start: SourceToken[] = []
diff --git a/tests/cst.ts b/tests/cst.ts
index 7100e8f6..3580c959 100644
--- a/tests/cst.ts
+++ b/tests/cst.ts
@@ -195,3 +195,9 @@ describe('CST.visit', () => {
     expect(visits).toBe(3)
   })
 })
+
+test('Line comment before unindented block-seq in block-map (eemeli/yaml#525)', () => {
+  const src = 'a:\n#\n- b'
+  const [doc] = Array.from(new Parser().parse(src))
+  expect(CST.stringify(doc)).toBe(src)
+})