diff --git a/src/hnswinsert.c b/src/hnswinsert.c
index f461963..19f2fee 100644
--- a/src/hnswinsert.c
+++ b/src/hnswinsert.c
@@ -561,6 +561,12 @@ HnswInsertTuple(Relation index, Datum *values, bool *isnull, ItemPointer heap_ti
 	element = HnswInitElement(heap_tid, m, ml, HnswGetMaxLevel(m));
 	element->vec = DatumGetVector(value);
 
+	/*
+	 * Get a shared lock for the duration of the insert. Use a page lock so it
+	 * does not interfere with buffer lock (or reads when vacuuming).
+	 */
+	LockPage(index, HNSW_METAPAGE_BLKNO, ShareLock);
+
 	/* Get entry point */
 	entryPoint = HnswGetEntryPoint(index);
 
@@ -568,7 +574,10 @@ HnswInsertTuple(Relation index, Datum *values, bool *isnull, ItemPointer heap_ti
 	if (entryPoint == NULL)
 	{
 		if (HnswAddEntryPoint(index, element, m, &entryPoint))
+		{
+			UnlockPage(index, HNSW_METAPAGE_BLKNO, ShareLock);
 			return true;
+		}
 	}
 
 	/* Insert element in graph */
@@ -580,6 +589,9 @@ HnswInsertTuple(Relation index, Datum *values, bool *isnull, ItemPointer heap_ti
 	/* Write to disk */
 	WriteElement(index, procinfo, collation, element, m, efConstruction, dup, entryPoint);
 
+	/* Release shared lock */
+	UnlockPage(index, HNSW_METAPAGE_BLKNO, ShareLock);
+
 	return true;
 }
 
diff --git a/src/hnswvacuum.c b/src/hnswvacuum.c
index e4db3e8..ee34039 100644
--- a/src/hnswvacuum.c
+++ b/src/hnswvacuum.c
@@ -5,6 +5,7 @@
 #include "commands/vacuum.h"
 #include "hnsw.h"
 #include "storage/bufmgr.h"
+#include "storage/lmgr.h"
 #include "utils/memutils.h"
 
 /*
@@ -256,6 +257,10 @@ RepairGraphEntryPoint(HnswVacuumState * vacuumstate)
 	 * ideal.
 	 */
 
+	/* Wait for inserts to complete */
+	LockPage(index, HNSW_METAPAGE_BLKNO, ExclusiveLock);
+	UnlockPage(index, HNSW_METAPAGE_BLKNO, ExclusiveLock);
+
 	if (!BlockNumberIsValid(highestPoint->blkno))
 		highestPoint = NULL;