diff --git a/scriptshifter/rest_api.py b/scriptshifter/rest_api.py
index ccf5d0e..5ed4206 100644
--- a/scriptshifter/rest_api.py
+++ b/scriptshifter/rest_api.py
@@ -8,6 +8,7 @@
 from smtplib import SMTP
 
 from flask import Flask, jsonify, render_template, request
+from werkzeug.exceptions import BadRequest
 
 from scriptshifter import EMAIL_FROM, EMAIL_TO, SMTP_HOST, SMTP_PORT
 from scriptshifter.exceptions import ApiError
@@ -46,6 +47,20 @@ def handle_exception(e: ApiError):
     }, e.status_code)
 
 
+@app.errorhandler(BadRequest)
+def handle_400(e):
+    if logging.DEBUG >= logging.root.level:
+        body = {
+            "debug": {
+                "form_data": request.form,
+            }
+        }
+    else:
+        body = ""
+
+    return body, 400
+
+
 @app.route("/", methods=["GET"])
 def index():
     return render_template(
@@ -108,9 +123,7 @@ def transliterate_req():
     except (NotImplementedError, ValueError) as e:
         return (str(e), 400)
 
-    return {
-            "output": out, "warnings": warnings,
-            "debug": {"form_data": request.form}}
+    return {"output": out, "warnings": warnings}
 
 
 @app.route("/feedback", methods=["POST"])