diff --git a/core/HalfLife2.cpp b/core/HalfLife2.cpp
index 53af3dc8..7600917b 100644
--- a/core/HalfLife2.cpp
+++ b/core/HalfLife2.cpp
@@ -1099,8 +1099,26 @@ int CHalfLife2::ReferenceToIndex(cell_t entRef)
 
 		return hndl.GetEntryIndex();
 	}
+	else
+	{
+		CEntInfo *pInfo = LookupEntity(entRef);
+		if (!pInfo)
+		{
+			return INVALID_EHANDLE_INDEX;
+		}
+		IServerUnknown *pUnk = static_cast<IServerUnknown *>(pInfo->m_pEntity);
+		if (!pUnk)
+		{
+			return INVALID_EHANDLE_INDEX;
+		}
+		CBaseEntity *pEntity = pUnk->GetBaseEntity();
+		if (!pEntity)
+		{
+			return INVALID_EHANDLE_INDEX; 
+		}
 
-	return entRef;
+		return entRef;
+	}
 }
 
 cell_t CHalfLife2::EntityToBCompatRef(CBaseEntity *pEntity)
diff --git a/plugins/include/halflife.inc b/plugins/include/halflife.inc
index ccb5bf90..38626f23 100644
--- a/plugins/include/halflife.inc
+++ b/plugins/include/halflife.inc
@@ -667,10 +667,11 @@ stock void DisplayAskConnectBox(int client, float time, const char[] ip, const c
 native int EntIndexToEntRef(int entity);
 
 /**
- * Retrieves the entity index from a reference.
+ * Retrieves the entity index from a reference or validates an entity index.
+ * The input ref is checked that it is still valid and refers to the same entity.
  *
- * @param ref           Entity reference.
- * @return              Entity index or -1 on invalid reference.
+ * @param ref           Entity reference or index.
+ * @return              Entity index or returns INVALID_ENT_REFERENCE if ref is invalid.
  */
 native int EntRefToEntIndex(int ref);