diff --git a/src/bitcoin-cli.cpp b/src/bitcoin-cli.cpp
--- a/src/bitcoin-cli.cpp
+++ b/src/bitcoin-cli.cpp
@@ -775,6 +775,7 @@
     assert(output_headers);
     evhttp_add_header(output_headers, "Host", host.c_str());
     evhttp_add_header(output_headers, "Connection", "close");
+    evhttp_add_header(output_headers, "Content-Type", "application/json");
     evhttp_add_header(
         output_headers, "Authorization",
         (std::string("Basic ") + EncodeBase64(strRPCUserColonPass)).c_str());