diff --git a/src/VecSim/vec_sim_common.h b/src/VecSim/vec_sim_common.h
index 9f6544d1b..9597c0489 100644
--- a/src/VecSim/vec_sim_common.h
+++ b/src/VecSim/vec_sim_common.h
@@ -276,6 +276,12 @@ typedef struct {
     double epsilon;   // Epsilon parameter for HNSW graph accuracy/latency for range search.
 } HNSWRuntimeParams;
 
+typedef struct {
+    size_t efRuntime;        // EF parameter for HNSW graph accuracy/latency for search.
+    double epsilon;          // Epsilon parameter for HNSW graph accuracy/latency for range search.
+    VecSimBool shouldRerank; // Whether to enable reranking for disk-based HNSW (True/False/Unset).
+} HNSWDiskRuntimeParams;
+
 typedef struct {
     size_t windowSize;     // Search window size for Vamana graph accuracy/latency tune.
     size_t bufferCapacity; // Search buffer capacity for Vamana graph accuracy/latency tune.
@@ -313,6 +319,7 @@ typedef enum {
 typedef struct {
     union {
         HNSWRuntimeParams hnswRuntimeParams;
+        HNSWDiskRuntimeParams hnswDiskRuntimeParams;
         SVSRuntimeParams svsRuntimeParams;
     };
     size_t batchSize;