diff --git a/activities/views/debug.py b/activities/views/debug.py
index 568a3b4..4272aef 100644
--- a/activities/views/debug.py
+++ b/activities/views/debug.py
@@ -24,10 +24,13 @@ class JsonViewer(FormView):
 
     def form_valid(self, form):
         raw_result = ""
+        uri = form.cleaned_data["uri"]
+        if "://" not in uri:
+            uri = "https://" + uri
         try:
             response = async_to_sync(SystemActor().signed_request)(
                 method="get",
-                uri=form.cleaned_data["uri"],
+                uri=uri,
             )
         except httpx.RequestError:
             result = "Request Error"
diff --git a/core/signatures.py b/core/signatures.py
index 12e9e97..fba6b5a 100644
--- a/core/signatures.py
+++ b/core/signatures.py
@@ -183,6 +183,8 @@ class HttpSignature:
         Performs an async request to the given path, with a document, signed
         as an identity.
         """
+        if "://" not in uri:
+            raise ValueError("URI does not contain a scheme")
         # Create the core header field set
         uri_parts = urlparse(uri)
         date_string = http_date()
@@ -200,9 +202,7 @@ class HttpSignature:
             body_bytes = b""
         # GET requests get implicit accept headers added
         if method == "get":
-            headers[
-                "Accept"
-            ] = 'application/ld+json; profile="https://www.w3.org/ns/activitystreams"'
+            headers["Accept"] = "application/ld+json"
         # Sign the headers
         signed_string = "\n".join(
             f"{name.lower()}: {value}" for name, value in headers.items()