diff --git a/src/stac_api_validator/validations.py b/src/stac_api_validator/validations.py
index 0e847b4..fdefc7c 100644
--- a/src/stac_api_validator/validations.py
+++ b/src/stac_api_validator/validations.py
@@ -1074,6 +1074,10 @@ def validate_collections(
                         r_session.headers,
                     )
 
+            if not collection:
+                warnings += f"[{Context.COLLECTIONS}] Collection parameter required for running all Collections validation"
+                return
+
             collection_url = f"{data_link['href']}/{collection}"
             _, body, resp_headers = retrieve(
                 Method.GET,