diff --git a/faiss/IndexHNSW.cpp b/faiss/IndexHNSW.cpp
index 4cc58d211c..d6739b69e8 100644
--- a/faiss/IndexHNSW.cpp
+++ b/faiss/IndexHNSW.cpp
@@ -237,19 +237,19 @@ void hnsw_search(
         idx_t n,
         const float* x,
         BlockResultHandler& bres,
-        const SearchParameters* params_in) {
+        const SearchParameters* params) {
     FAISS_THROW_IF_NOT_MSG(
             index->storage,
             "No storage index, please use IndexHNSWFlat (or variants) "
             "instead of IndexHNSW directly");
-    const SearchParametersHNSW* params = nullptr;
     const HNSW& hnsw = index->hnsw;
 
     int efSearch = hnsw.efSearch;
-    if (params_in) {
-        params = dynamic_cast<const SearchParametersHNSW*>(params_in);
-        FAISS_THROW_IF_NOT_MSG(params, "params type invalid");
-        efSearch = params->efSearch;
+    if (params) {
+        if (const SearchParametersHNSW* hnsw_params =
+                    dynamic_cast<const SearchParametersHNSW*>(params)) {
+            efSearch = hnsw_params->efSearch;
+        }
     }
     size_t n1 = 0, n2 = 0, ndis = 0, nhops = 0;
 
@@ -294,13 +294,13 @@ void IndexHNSW::search(
         idx_t k,
         float* distances,
         idx_t* labels,
-        const SearchParameters* params_in) const {
+        const SearchParameters* params) const {
     FAISS_THROW_IF_NOT(k > 0);
 
     using RH = HeapBlockResultHandler<HNSW::C>;
     RH bres(n, distances, labels, k);
 
-    hnsw_search(this, n, x, bres, params_in);
+    hnsw_search(this, n, x, bres, params);
 
     if (is_similarity_metric(this->metric_type)) {
         // we need to revert the negated distances
@@ -408,17 +408,10 @@ void IndexHNSW::search_level_0(
         idx_t* labels,
         int nprobe,
         int search_type,
-        const SearchParameters* params_in) const {
+        const SearchParameters* params) const {
     FAISS_THROW_IF_NOT(k > 0);
     FAISS_THROW_IF_NOT(nprobe > 0);
 
-    const SearchParametersHNSW* params = nullptr;
-
-    if (params_in) {
-        params = dynamic_cast<const SearchParametersHNSW*>(params_in);
-        FAISS_THROW_IF_NOT_MSG(params, "params type invalid");
-    }
-
     storage_idx_t ntotal = hnsw.levels.size();
 
     using RH = HeapBlockResultHandler<HNSW::C>;
diff --git a/faiss/impl/HNSW.cpp b/faiss/impl/HNSW.cpp
index 09b10e2b97..ece0281221 100644
--- a/faiss/impl/HNSW.cpp
+++ b/faiss/impl/HNSW.cpp
@@ -590,15 +590,22 @@ int search_from_candidates(
         HNSWStats& stats,
         int level,
         int nres_in,
-        const SearchParametersHNSW* params) {
+        const SearchParameters* params) {
     int nres = nres_in;
     int ndis = 0;
 
     // can be overridden by search params
-    bool do_dis_check = params ? params->check_relative_distance
-                               : hnsw.check_relative_distance;
-    int efSearch = params ? params->efSearch : hnsw.efSearch;
-    const IDSelector* sel = params ? params->sel : nullptr;
+    bool do_dis_check = hnsw.check_relative_distance;
+    int efSearch = hnsw.efSearch;
+    const IDSelector* sel = nullptr;
+    if (params) {
+        if (const SearchParametersHNSW* hnsw_params =
+                    dynamic_cast<const SearchParametersHNSW*>(params)) {
+            do_dis_check = hnsw_params->check_relative_distance;
+            efSearch = hnsw_params->efSearch;
+        }
+        sel = params->sel;
+    }
 
     C::T threshold = res.threshold;
     for (int i = 0; i < candidates.size(); i++) {
@@ -920,15 +927,22 @@ HNSWStats HNSW::search(
         DistanceComputer& qdis,
         ResultHandler<C>& res,
         VisitedTable& vt,
-        const SearchParametersHNSW* params) const {
+        const SearchParameters* params) const {
     HNSWStats stats;
     if (entry_point == -1) {
         return stats;
     }
     int k = extract_k_from_ResultHandler(res);
 
-    bool bounded_queue =
-            params ? params->bounded_queue : this->search_bounded_queue;
+    bool bounded_queue = this->search_bounded_queue;
+    int efSearch = this->efSearch;
+    if (params) {
+        if (const SearchParametersHNSW* hnsw_params =
+                    dynamic_cast<const SearchParametersHNSW*>(params)) {
+            bounded_queue = hnsw_params->bounded_queue;
+            efSearch = hnsw_params->efSearch;
+        }
+    }
 
     //  greedy search on upper levels
     storage_idx_t nearest = entry_point;
@@ -940,7 +954,7 @@ HNSWStats HNSW::search(
         stats.combine(local_stats);
     }
 
-    int ef = std::max(params ? params->efSearch : efSearch, k);
+    int ef = std::max(efSearch, k);
     if (bounded_queue) { // this is the most common branch
         MinimaxHeap candidates(ef);
 
@@ -980,9 +994,17 @@ void HNSW::search_level_0(
         int search_type,
         HNSWStats& search_stats,
         VisitedTable& vt,
-        const SearchParametersHNSW* params) const {
+        const SearchParameters* params) const {
     const HNSW& hnsw = *this;
-    auto efSearch = params ? params->efSearch : hnsw.efSearch;
+
+    auto efSearch = hnsw.efSearch;
+    if (params) {
+        if (const SearchParametersHNSW* hnsw_params =
+                    dynamic_cast<const SearchParametersHNSW*>(params)) {
+            efSearch = hnsw_params->efSearch;
+        }
+    }
+
     int k = extract_k_from_ResultHandler(res);
 
     if (search_type == 1) {
diff --git a/faiss/impl/HNSW.h b/faiss/impl/HNSW.h
index aad26b1eda..f79f1c1199 100644
--- a/faiss/impl/HNSW.h
+++ b/faiss/impl/HNSW.h
@@ -200,7 +200,7 @@ struct HNSW {
             DistanceComputer& qdis,
             ResultHandler<C>& res,
             VisitedTable& vt,
-            const SearchParametersHNSW* params = nullptr) const;
+            const SearchParameters* params = nullptr) const;
 
     /// search only in level 0 from a given vertex
     void search_level_0(
@@ -212,7 +212,7 @@ struct HNSW {
             int search_type,
             HNSWStats& search_stats,
             VisitedTable& vt,
-            const SearchParametersHNSW* params = nullptr) const;
+            const SearchParameters* params = nullptr) const;
 
     void reset();
 
@@ -264,7 +264,7 @@ int search_from_candidates(
         HNSWStats& stats,
         int level,
         int nres_in = 0,
-        const SearchParametersHNSW* params = nullptr);
+        const SearchParameters* params = nullptr);
 
 HNSWStats greedy_update_nearest(
         const HNSW& hnsw,