diff --git a/CHANGELOG.md b/CHANGELOG.md
index 00c8be1..af75e5b 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,6 +1,7 @@
 ## 0.5.1 (unreleased)
 
 - Improved performance of index scans for IVFFlat after updates and deletes
+- Fixed locking for index scans for HNSW
 
 ## 0.5.0 (2023-08-28)
 
diff --git a/src/hnswscan.c b/src/hnswscan.c
index d12e697..a7f6997 100644
--- a/src/hnswscan.c
+++ b/src/hnswscan.c
@@ -114,6 +114,12 @@ hnswbeginscan(Relation index, int nkeys, int norderbys)
 
 	scan->opaque = so;
 
+	/*
+	 * Get a shared lock. This allows vacuum to ensure no in-flight scans
+	 * before marking tuples as deleted.
+	 */
+	LockPage(scan->indexRelation, HNSW_SCAN_LOCK, ShareLock);
+
 	return scan;
 }
 
@@ -164,17 +170,8 @@ hnswgettuple(IndexScanDesc scan, ScanDirection dir)
 		/* Get scan value */
 		value = GetScanValue(scan);
 
-		/*
-		 * Get a shared lock. This allows vacuum to ensure no in-flight scans
-		 * before marking tuples as deleted.
-		 */
-		LockPage(scan->indexRelation, HNSW_SCAN_LOCK, ShareLock);
-
 		so->w = GetScanItems(scan, value);
 
-		/* Release shared lock */
-		UnlockPage(scan->indexRelation, HNSW_SCAN_LOCK, ShareLock);
-
 		so->first = false;
 	}
 
@@ -236,6 +233,9 @@ hnswendscan(IndexScanDesc scan)
 	if (BufferIsValid(so->buf))
 		ReleaseBuffer(so->buf);
 
+	/* Release shared lock */
+	UnlockPage(scan->indexRelation, HNSW_SCAN_LOCK, ShareLock);
+
 	MemoryContextDelete(so->tmpCtx);
 
 	pfree(so);