diff --git a/README.md b/README.md
index fec2466cf1e7110cb52ef3931465be6d96a5aa92..ce996c6a2afbc19a0e12f52d952c8f91b1d8f8d2 100644
--- a/README.md
+++ b/README.md
@@ -147,6 +147,7 @@ You can also get a string representation (serialize):
 std::string s = j.dump();    // {\"happy\":true,\"pi\":3.141}
 
 // serialization with pretty printing
+// pass in the amount of spaces to indent
 std::cout << j.dump(4) << std::endl;
 // {
 //     "happy": true,