diff --git a/src/pip/_internal/resolution/resolvelib/candidates.py b/src/pip/_internal/resolution/resolvelib/candidates.py
index e1b3584af60..2db00297d81 100644
--- a/src/pip/_internal/resolution/resolvelib/candidates.py
+++ b/src/pip/_internal/resolution/resolvelib/candidates.py
@@ -274,6 +274,8 @@ def __init__(
                 )
 
         if cache_entry is not None:
+            assert ireq.link.is_wheel
+            assert ireq.link.is_file
             if cache_entry.persistent and template.link is template.original_link:
                 ireq.is_wheel_from_cache = True
             if cache_entry.origin is not None: