diff --git a/progenitor-client/src/progenitor_client.rs b/progenitor-client/src/progenitor_client.rs
index 2be24d7..7096294 100644
--- a/progenitor-client/src/progenitor_client.rs
+++ b/progenitor-client/src/progenitor_client.rs
@@ -372,7 +372,7 @@ impl<E> RequestBuilderExt<E> for RequestBuilder {
                     "application/x-www-form-urlencoded",
                 ),
             )
-            .body(serde_json::to_vec(&body).map_err(|_| {
+            .body(serde_urlencoded::to_string(&body).map_err(|_| {
                 Error::InvalidRequest("failed to serialize body".to_string())
             })?))
     }
diff --git a/progenitor-impl/src/lib.rs b/progenitor-impl/src/lib.rs
index 0fcedd8..4a54054 100644
--- a/progenitor-impl/src/lib.rs
+++ b/progenitor-impl/src/lib.rs
@@ -400,7 +400,7 @@ impl Generator {
             "percent-encoding = \"2.1\"",
             "reqwest = { version = \"0.11\", features = [\"json\", \"stream\"] }",
             "serde = { version = \"1.0\", features = [\"derive\"] }",
-            "serde_urlencoded = 0.7",
+            "serde_urlencoded = \"0.7\"",
         ];
         if self.type_space.uses_regress() {
             deps.push("regress = 0.4")