diff --git a/index.html b/index.html
index 3739c6f..28a02fc 100644
--- a/index.html
+++ b/index.html
@@ -161,7 +161,7 @@ function run() {
 	req.onreadystatechange = function() {
 		switch (req.status) {
 			case 200:
-				if (req.getResponseHeader("Content-Type") === "img/png") {
+				if (req.getResponseHeader("Content-Type") === "image/png") {
 					output.innerHTML = '<img src="data:image/png;base64,' + req.responseText + '"/>';
 				} else {
 					output.innerHTML = req.responseText;
diff --git a/main.go b/main.go
index d508957..0665c09 100644
--- a/main.go
+++ b/main.go
@@ -76,6 +76,7 @@ func (t *Tool) execute(in io.Reader, w http.ResponseWriter) {
 	if e := cmd.Run(); e == nil {
 		if t.ContentType != "" {
 			w.Header().Add("Content-Type", t.ContentType)
+			w.Header().Set("Content-Transfer-Encoding", "base64")
 			io.Copy(base64.NewEncoder(base64.StdEncoding, w), buf)
 		} else {
 			w.Header().Add("Content-Type", "image/svg+xml")
diff --git a/tools.json b/tools.json
index f19fa5d..1158b14 100644
--- a/tools.json
+++ b/tools.json
@@ -32,7 +32,7 @@
 		"Args":    ["+O-", "-D", "+A0.9", "+R3"], 
 		"Suffix":  ".pov",
 		"NeedsFile": true,
-		"ContentType": "img/png",
+		"ContentType": "image/png",
 		"Description": "Povray, raytracer",
 		"BgColor": "Orange",
 		"Documentation": {