diff --git a/core/vector_store/chunk_v2_store.py b/core/vector_store/chunk_v2_store.py
index 2d8990cc..63366d3a 100644
--- a/core/vector_store/chunk_v2_store.py
+++ b/core/vector_store/chunk_v2_store.py
@@ -399,8 +399,10 @@ async def query_similar(
             )
 
             async with self.get_session_with_retry() as session:
-                # PostgreSQL SET doesn't support parameterized values; safe since ivfflat_probes is a validated int
-                await session.execute(text(f"SET LOCAL ivfflat.probes = {self.ivfflat_probes}"))
+                # Use set_config() for parameterized config - SET doesn't support parameters
+                await session.execute(
+                    text("SELECT set_config('ivfflat.probes', :probes, true)"), {"probes": str(self.ivfflat_probes)}
+                )
                 result = await session.execute(query)
                 rows = result.all()
 
diff --git a/core/vector_store/pgvector_store.py b/core/vector_store/pgvector_store.py
index 2f86e4d2..66db9e09 100644
--- a/core/vector_store/pgvector_store.py
+++ b/core/vector_store/pgvector_store.py
@@ -458,8 +458,10 @@ async def query_similar(
         """
         try:
             async with self.get_session_with_retry() as session:
-                # PostgreSQL SET doesn't support parameterized values; safe since ivfflat_probes is a validated int
-                await session.execute(text(f"SET LOCAL ivfflat.probes = {self.ivfflat_probes}"))
+                # Use set_config() for parameterized config - SET doesn't support parameters
+                await session.execute(
+                    text("SELECT set_config('ivfflat.probes', :probes, true)"), {"probes": str(self.ivfflat_probes)}
+                )
                 # Build query with cosine distance calculation, which is normalized to [0, 2].
                 # A distance of 0 is perfect similarity.
                 distance = VectorEmbedding.embedding.op("<=>")(query_embedding)