diff --git a/CHANGELOG.md b/CHANGELOG.md
index 9e0482b..6d769b4 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -14,6 +14,10 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - Derive `Hash` on requests types. [#114](https://github.com/jeertmans/languagetool-rust/pull/114)
 - Use Codspeed and `check-changelog` actions. [#121](https://github.com/jeertmans/languagetool-rust/pull/121)
 
+### Fixed
+
+- Fixed api calls to language tool server to adhere to spec. Pass POST calls as `application/x-www-form-urlencoded`. [#129](https://github.com/jeertmans/languagetool-rust/pull/129)
+
 ## [2.1.4](https://github.com/jeertmans/languagetool-rust/compare/v2.1.3...v2.1.4)
 
 ### Fixed
diff --git a/src/lib/server.rs b/src/lib/server.rs
index 8c38b1b..bb37987 100644
--- a/src/lib/server.rs
+++ b/src/lib/server.rs
@@ -11,7 +11,7 @@ use crate::{
 };
 #[cfg(feature = "cli")]
 use clap::Args;
-use reqwest::Client;
+use reqwest::{header::{HeaderValue, ACCEPT}, Client};
 use serde::{Deserialize, Serialize};
 use serde_json::Value;
 use std::{io, path::PathBuf, time::Instant};
@@ -372,7 +372,8 @@ impl ServerClient {
         match self
             .client
             .post(format!("{0}/check", self.api))
-            .query(request)
+            .header(ACCEPT, HeaderValue::from_static("application/json"))
+            .form(request)
             .send()
             .await
         {
@@ -485,6 +486,7 @@ impl ServerClient {
         match self
             .client
             .get(format!("{}/words", self.api))
+            .header(ACCEPT, HeaderValue::from_static("application/json"))
             .query(request)
             .send()
             .await
@@ -508,7 +510,8 @@ impl ServerClient {
         match self
             .client
             .post(format!("{}/words/add", self.api))
-            .query(request)
+            .header(ACCEPT, HeaderValue::from_static("application/json"))
+            .form(request)
             .send()
             .await
         {
@@ -531,7 +534,8 @@ impl ServerClient {
         match self
             .client
             .post(format!("{}/words/delete", self.api))
-            .query(request)
+            .header(ACCEPT, HeaderValue::from_static("application/json"))
+            .form(request)
             .send()
             .await
         {