diff --git a/CoreMetrics/CoreMetrics.cs b/CoreMetrics/CoreMetrics.cs
index a1c10af5d..5be9d35ca 100644
--- a/CoreMetrics/CoreMetrics.cs
+++ b/CoreMetrics/CoreMetrics.cs
@@ -64,7 +64,7 @@ private JObject GetBlocksTime(uint nBlocks, uint lastHeight)
             if (nBlocks >= Blockchain.Singleton.Height)
             {
                 JObject json = new JObject();
-                return json["error"] = "Requested number of blocks timestamps exceeds quantity of known blocks " + Blockchain.Singleton.Height;
+                return json["error"] = "Requested number of blocks timestamps " + nBlocks + " exceeds quantity of known blocks " + Blockchain.Singleton.Height;
             }
 
             if (nBlocks <= 0)
@@ -74,8 +74,8 @@ private JObject GetBlocksTime(uint nBlocks, uint lastHeight)
             }
 
             JArray array = new JArray();
-            uint heightToBegin = lastHeight > 0 ? lastHeight - nBlocks : Blockchain.Singleton.Height - nBlocks;
-            for (uint i = heightToBegin; i <= Blockchain.Singleton.HeaderHeight; i++)
+            uint heightToBegin = lastHeight > 0 ? lastHeight - nBlocks : (Blockchain.Singleton.Height - 1) - nBlocks;
+            for (uint i = heightToBegin; i <= heightToBegin + nBlocks; i++)
             {
                 JObject json = new JObject();
                 Header header = Blockchain.Singleton.Store.GetHeader(i);