diff --git a/Coinbase.Net/Clients/AdvancedTradeApi/CoinbaseRestClientAdvancedTradeApiExchangeData.cs b/Coinbase.Net/Clients/AdvancedTradeApi/CoinbaseRestClientAdvancedTradeApiExchangeData.cs
index 3bed539..d044321 100644
--- a/Coinbase.Net/Clients/AdvancedTradeApi/CoinbaseRestClientAdvancedTradeApiExchangeData.cs
+++ b/Coinbase.Net/Clients/AdvancedTradeApi/CoinbaseRestClientAdvancedTradeApiExchangeData.cs
@@ -105,8 +105,8 @@ public async Task<WebCallResult<IEnumerable<CoinbaseKline>>> GetKlinesAsync(stri
         {
             var parameters = new ParameterCollection();
             parameters.AddEnum("granularity", klineInterval);
-            parameters.AddOptionalMillisecondsString("start", startTime);
-            parameters.AddOptionalMillisecondsString("end", endTime);
+            parameters.AddOptionalSecondsString("start", startTime);
+            parameters.AddOptionalSecondsString("end", endTime);
             parameters.AddOptional("limit", limit);
 
             RequestDefinition request;