diff --git a/src/ripple/net/impl/RPCCall.cpp b/src/ripple/net/impl/RPCCall.cpp
index c392fb46a..741240db8 100644
--- a/src/ripple/net/impl/RPCCall.cpp
+++ b/src/ripple/net/impl/RPCCall.cpp
@@ -1197,6 +1197,15 @@ std::string JSONRPCRequest (std::string const& strMethod, Json::Value const& par
     return to_string (request) + "\n";
 }
 
+namespace
+{
+    // Special local exception type thrown when request can't be parsed.
+    class RequestNotParseable : public std::runtime_error
+    {
+        using std::runtime_error::runtime_error; // Inherit constructors
+    };
+};
+
 struct RPCCallImp
 {
     // VFALCO NOTE Is this a to-do comment or a doc comment?
@@ -1228,7 +1237,8 @@ struct RPCCallImp
 
             // Parse reply
             JLOG (j.debug()) << "RPC reply: " << strData << std::endl;
-
+            if (strData.find("Unable to parse request") == 0)
+                Throw<RequestNotParseable> (strData);
             Json::Reader    reader;
             Json::Value     jvReply;
             if (!reader.parse (strData, jvReply))
@@ -1440,6 +1450,12 @@ rpcClient(std::vector<std::string> const& args,
         // YYY We could have a command line flag for single line output for scripts.
         // YYY We would intercept output here and simplify it.
     }
+    catch (RequestNotParseable& e)
+    {
+        jvOutput                = rpcError(rpcINVALID_PARAMS);
+        jvOutput["error_what"]  = e.what();
+        nRet                    = rpcINVALID_PARAMS;
+    }
     catch (std::exception& e)
     {
         jvOutput                = rpcError (rpcINTERNAL);
diff --git a/src/ripple/rpc/impl/ServerHandlerImp.cpp b/src/ripple/rpc/impl/ServerHandlerImp.cpp
index 796b0a8a6..ae484b02e 100644
--- a/src/ripple/rpc/impl/ServerHandlerImp.cpp
+++ b/src/ripple/rpc/impl/ServerHandlerImp.cpp
@@ -569,7 +569,8 @@ ServerHandlerImp::processRequest (Port const& port,
             ! jsonOrig ||
             ! (jsonOrig.isObject () || jsonOrig.isArray()))
         {
-            HTTPReply (400, "Unable to parse request", output, rpcJ);
+            HTTPReply (400, "Unable to parse request: " +
+                       reader.getFormatedErrorMessages(), output, rpcJ);
             return;
         }
     }
diff --git a/src/test/rpc/LedgerRPC_test.cpp b/src/test/rpc/LedgerRPC_test.cpp
index 3c74ceb59..3f28b079b 100644
--- a/src/test/rpc/LedgerRPC_test.cpp
+++ b/src/test/rpc/LedgerRPC_test.cpp
@@ -121,6 +121,20 @@ class LedgerRPC_test : public beast::unit_test::suite
             checkErrorValue(jrr, "invalidParams", "Invalid parameters.");
         }
 
+        {
+            // Request a ledger with a very large (double) sequence.
+            auto const ret = env.rpc (
+                "json", "ledger", "{ \"ledger_index\" : 2e15 }");
+            BEAST_EXPECT (RPC::contains_error(ret));
+            BEAST_EXPECT (ret[jss::error_message] == "Invalid parameters.");
+        }
+
+        {
+            // Request a ledger with very large (integer) sequence.
+            auto const ret = env.rpc (
+                "json", "ledger", "{ \"ledger_index\" : 1000000000000000 }");
+            checkErrorValue(ret, "invalidParams", "Invalid parameters.");
+        }
     }
 
     void testLedgerCurrent()
diff --git a/src/test/server/ServerStatus_test.cpp b/src/test/server/ServerStatus_test.cpp
index 6a48d796c..ea89db89a 100644
--- a/src/test/server/ServerStatus_test.cpp
+++ b/src/test/server/ServerStatus_test.cpp
@@ -893,7 +893,7 @@ class ServerStatus_test :
             boost::beast::http::response<boost::beast::http::string_body> resp;
             doHTTPRequest(env, yield, false, resp, ec, "{}");
             BEAST_EXPECT(resp.result() == boost::beast::http::status::bad_request);
-            BEAST_EXPECT(resp.body() == "Unable to parse request\r\n");
+            BEAST_EXPECT(resp.body() == "Unable to parse request: \r\n");
         }
 
         Json::Value jv;