diff --git a/src/VecSim/vec_sim_common.h b/src/VecSim/vec_sim_common.h
index 993f46e9b..22f54a1e6 100644
--- a/src/VecSim/vec_sim_common.h
+++ b/src/VecSim/vec_sim_common.h
@@ -138,7 +138,7 @@ typedef int (*SubmitCB)(void *job_queue, void *index_ctx, AsyncJob **jobs, JobCa
 /**
  * Callback signature for throttle control in disk tiered index.
  */
-typedef void (*ThrottleCB)(void);
+typedef int (*ThrottleCB)(void);
 
 /**
  * @brief Index initialization parameters.
@@ -208,9 +208,9 @@ typedef struct {
 } TieredHNSWParams;
 
 // A struct that contains HNSW Disk tiered index specific params.
+// Consider removing and use TieredHNSWParams instead if they both share swapJobThreshold
 typedef struct {
-    ThrottleCB enableThrottleCB;  // call to enable postponing of Redis commands
-    ThrottleCB disableThrottleCB; // call to disable postponing of Redis commands
+    char _placeholder; // Reserved for future fields and avoid compiler errors
 } TieredHNSWDiskParams;
 
 // A struct that contains SVS tiered index specific params.