diff --git a/jsoncmd.go b/jsoncmd.go
index 130898db..f6e8f4bf 100644
--- a/jsoncmd.go
+++ b/jsoncmd.go
@@ -324,7 +324,12 @@ func ParseMarshaledCmd(b []byte) (Cmd, error) {
 		// None of the standard Bitcoin RPC methods matched.  Try
 		// registered custom commands.
 		if c, ok := customCmds[r.Method]; ok {
-			return c.parser(&r)
+			cmd, err := c.parser(&r)
+			if err != nil {
+				cmd = newUnparsableCmd(r.Id, r.Method)
+				return cmd, err
+			}
+			return cmd, nil
 		}
 	}
 
diff --git a/test_coverage.txt b/test_coverage.txt
index 1f15ea0c..7f95a4c5 100644
--- a/test_coverage.txt
+++ b/test_coverage.txt
@@ -263,39 +263,39 @@ github.com/conformal/btcjson/jsoncmd.go		 GetInfoCmd.Id				 100.00% (1/1)
 github.com/conformal/btcjson/jsoncmd.go		 GetInfoCmd.SetId			 100.00% (1/1)
 github.com/conformal/btcjson/jsoncmd.go		 GetInfoCmd.Method			 100.00% (1/1)
 github.com/conformal/btcjson/jsonapi.go		 CreateMessageWithId			 96.18% (327/340)
-github.com/conformal/btcjson/jsoncmd.go		 SendManyCmd.MarshalJSON		 92.86% (13/14)
 github.com/conformal/btcjson/jsoncmd.go		 SendFromCmd.MarshalJSON		 92.86% (13/14)
-github.com/conformal/btcjson/jsoncmd.go		 ParseMarshaledCmd			 91.86% (79/86)
+github.com/conformal/btcjson/jsoncmd.go		 SendManyCmd.MarshalJSON		 92.86% (13/14)
 github.com/conformal/btcjson/jsoncmd.go		 MoveCmd.MarshalJSON			 91.67% (11/12)
 github.com/conformal/btcjson/jsoncmd.go		 ListTransactionsCmd.MarshalJSON	 90.91% (10/11)
 github.com/conformal/btcjson/jsoncmd.go		 SendToAddressCmd.MarshalJSON		 90.91% (10/11)
 github.com/conformal/btcjson/jsoncmd.go		 ListUnspentCmd.MarshalJSON		 90.91% (10/11)
 github.com/conformal/btcjson/jsoncmd.go		 ImportPrivKeyCmd.MarshalJSON		 90.00% (9/10)
-github.com/conformal/btcjson/jsoncmd.go		 ListReceivedByAddressCmd.MarshalJSON	 88.89% (8/9)
-github.com/conformal/btcjson/jsoncmd.go		 VerifyChainCmd.MarshalJSON		 88.89% (8/9)
 github.com/conformal/btcjson/jsoncmd.go		 GetBalanceCmd.MarshalJSON		 88.89% (8/9)
-github.com/conformal/btcjson/jsoncmd.go		 ListSinceBlockCmd.MarshalJSON		 88.89% (8/9)
+github.com/conformal/btcjson/jsoncmd.go		 ListReceivedByAccountCmd.MarshalJSON	 88.89% (8/9)
+github.com/conformal/btcjson/jsoncmd.go		 NewGetNetworkHashPSCmd			 88.89% (8/9)
 github.com/conformal/btcjson/jsoncmd.go		 NewVerifyChainCmd			 88.89% (8/9)
+github.com/conformal/btcjson/jsoncmd.go		 VerifyChainCmd.MarshalJSON		 88.89% (8/9)
+github.com/conformal/btcjson/jsoncmd.go		 ListSinceBlockCmd.MarshalJSON		 88.89% (8/9)
+github.com/conformal/btcjson/jsoncmd.go		 ListReceivedByAddressCmd.MarshalJSON	 88.89% (8/9)
 github.com/conformal/btcjson/jsoncmd.go		 AddMultisigAddressCmd.MarshalJSON	 88.89% (8/9)
 github.com/conformal/btcjson/jsoncmd.go		 GetNetworkHashPSCmd.MarshalJSON	 88.89% (8/9)
-github.com/conformal/btcjson/jsoncmd.go		 NewGetNetworkHashPSCmd			 88.89% (8/9)
-github.com/conformal/btcjson/jsoncmd.go		 ListReceivedByAccountCmd.MarshalJSON	 88.89% (8/9)
+github.com/conformal/btcjson/jsoncmd.go		 ParseMarshaledCmd			 87.78% (79/90)
 github.com/conformal/btcjson/jsoncmd.go		 GetReceivedByAccountCmd.MarshalJSON	 87.50% (7/8)
 github.com/conformal/btcjson/jsoncmd.go		 SubmitBlockCmd.MarshalJSON		 87.50% (7/8)
 github.com/conformal/btcjson/jsoncmd.go		 GetReceivedByAddressCmd.MarshalJSON	 87.50% (7/8)
-github.com/conformal/btcjson/jsoncmd.go		 SetGenerateCmd.MarshalJSON		 87.50% (7/8)
 github.com/conformal/btcjson/jsoncmd.go		 GetRawTransactionCmd.MarshalJSON	 87.50% (7/8)
 github.com/conformal/btcjson/jsoncmd.go		 CreateRawTransactionCmd.MarshalJSON	 87.50% (7/8)
 github.com/conformal/btcjson/jsoncmd.go		 NewRawCmd				 87.50% (7/8)
 github.com/conformal/btcjson/jsoncmd.go		 SendRawTransactionCmd.MarshalJSON	 87.50% (7/8)
+github.com/conformal/btcjson/jsoncmd.go		 SetGenerateCmd.MarshalJSON		 87.50% (7/8)
 github.com/conformal/btcjson/jsoncmd.go		 GetAddedNodeInfoCmd.MarshalJSON	 85.71% (6/7)
-github.com/conformal/btcjson/jsoncmd.go		 GetRawChangeAddressCmd.MarshalJSON	 85.71% (6/7)
 github.com/conformal/btcjson/jsoncmd.go		 GetNewAddressCmd.MarshalJSON		 85.71% (6/7)
 github.com/conformal/btcjson/jsoncmd.go		 GetBlockTemplateCmd.MarshalJSON	 85.71% (6/7)
-github.com/conformal/btcjson/jsoncmd.go		 GetRawMempoolCmd.MarshalJSON		 85.71% (6/7)
-github.com/conformal/btcjson/jsoncmd.go		 GetWorkCmd.MarshalJSON			 85.71% (6/7)
 github.com/conformal/btcjson/jsoncmd.go		 ListAccountsCmd.MarshalJSON		 85.71% (6/7)
+github.com/conformal/btcjson/jsoncmd.go		 GetRawChangeAddressCmd.MarshalJSON	 85.71% (6/7)
 github.com/conformal/btcjson/jsoncmd.go		 KeyPoolRefillCmd.MarshalJSON		 85.71% (6/7)
+github.com/conformal/btcjson/jsoncmd.go		 GetWorkCmd.MarshalJSON			 85.71% (6/7)
+github.com/conformal/btcjson/jsoncmd.go		 GetRawMempoolCmd.MarshalJSON		 85.71% (6/7)
 github.com/conformal/btcjson/jsoncmd.go		 HelpCmd.MarshalJSON			 85.71% (6/7)
 github.com/conformal/btcjson/jsoncmd.go		 NewGetRawChangeAddressCmd		 83.33% (5/6)
 github.com/conformal/btcjson/jsoncmd.go		 NewGetReceivedByAddressCmd		 83.33% (5/6)
@@ -462,5 +462,5 @@ github.com/conformal/btcjson/jsoncmd.go		 unparsableCmd.Method			 0.00% (0/1)
 github.com/conformal/btcjson/jsonapi.go		 TlsRpcRawCommand			 0.00% (0/1)
 github.com/conformal/btcjson/jsonapi.go		 RpcRawCommand				 0.00% (0/1)
 github.com/conformal/btcjson/jsonresults.go	 Vin.IsCoinBase				 0.00% (0/1)
-github.com/conformal/btcjson			 --------------------------------------- 78.37% (2348/2996)
+github.com/conformal/btcjson			 --------------------------------------- 78.27% (2348/3000)