diff --git a/lti/deep_linking.py b/lti/deep_linking.py
index e7e69f8f..044dfc33 100644
--- a/lti/deep_linking.py
+++ b/lti/deep_linking.py
@@ -201,7 +201,8 @@ class SelectMediaView(View):
                 lti_content_items.append(lti_item)
 
             # Create JWT payload
-            tool_issuer = request.build_absolute_uri('/')[:-1]
+            # Use client_id as issuer to avoid "wrong consumer key" errors in Moodle
+            tool_issuer = platform.client_id
 
             # Per LTI spec, aud should be the platform's issuer URL
             # Try just the platform URL (some Moodle versions don't accept arrays)