diff --git a/src/htmx.js b/src/htmx.js
index 0da9cf43..33a96726 100644
--- a/src/htmx.js
+++ b/src/htmx.js
@@ -3111,6 +3111,11 @@ return (function () {
 
 
             var headers = getHeaders(elt, target, promptResponse);
+
+            if (verb !== 'get' && !usesFormData(elt)) {
+                headers['Content-Type'] = 'application/x-www-form-urlencoded';
+            }
+
             if (etc.headers) {
                 headers = mergeObjects(headers, etc.headers);
             }
@@ -3124,10 +3129,6 @@ return (function () {
             var allParameters = mergeObjects(rawParameters, expressionVars);
             var filteredParameters = filterValues(allParameters, elt);
 
-            if (verb !== 'get' && !usesFormData(elt)) {
-                headers['Content-Type'] = 'application/x-www-form-urlencoded';
-            }
-
             if (htmx.config.getCacheBusterParam && verb === 'get') {
                 filteredParameters['org.htmx.cache-buster'] = getRawAttribute(target, "id") || "true";
             }
diff --git a/test/core/api.js b/test/core/api.js
index 53f5960a..431633d6 100644
--- a/test/core/api.js
+++ b/test/core/api.js
@@ -273,6 +273,44 @@ describe("Core htmx API test", function(){
         div.innerHTML.should.equal("Clicked!");
     });
 
+    it('ajax api Content-Type header is application/x-www-form-urlencoded', function(){
+
+        this.server.respondWith("POST", "/test", function (xhr) {
+            var params = getParameters(xhr);
+            xhr.requestHeaders['Content-Type'].should.equal('application/x-www-form-urlencoded;charset=utf-8');
+            params['i1'].should.equal("test");
+            xhr.respond(200, {}, "Clicked!")
+        });
+        var div = make("<div id='d1'></div>");
+        htmx.ajax("POST", "/test", {target:"#d1", values:{i1: 'test'}})
+        this.server.respond();
+        div.innerHTML.should.equal("Clicked!");
+    });
+
+    it('ajax api Content-Type header override to application/json', function(){
+
+        this.server.respondWith("POST", "/test", function (xhr) {
+            var params = getParameters(xhr);
+            xhr.requestHeaders['Content-Type'].should.equal('application/json;charset=utf-8');
+            params['i1'].should.equal("test");
+            xhr.respond(200, {}, "Clicked!");
+        });
+
+        var div = make("<div id='d1'></div>");
+        htmx.ajax('POST',"/test", {
+                target:'#d1',
+                swap:'innerHTML',
+                headers: {
+                    'Content-Type': 'application/json'
+                },
+                values:{i1: 'test'}
+        })
+
+        this.server.respond();
+        div.innerHTML.should.equal("Clicked!");
+    });
+
+
     it('can re-init with new attributes', function () {
         this.server.respondWith("PATCH", "/test", "patch");
         this.server.respondWith("DELETE", "/test", "delete");