diff --git a/tmt/steps/prepare/install.py b/tmt/steps/prepare/install.py
index 429c35ed3c..1b6854e0e4 100644
--- a/tmt/steps/prepare/install.py
+++ b/tmt/steps/prepare/install.py
@@ -614,9 +614,13 @@ def go(
                 exclude=self.data.exclude,
                 guest=guest)
 
+        elif guest.facts.package_manager is None:
+            raise tmt.utils.PrepareError('Unrecognized package manager.')
+
         else:
             raise tmt.utils.PrepareError(
-                'No supported package manager found.')
+                f"Package manager '{guest.facts.package_manager}' "
+                "is not supported by 'prepare/install'.")
 
         # Enable copr repositories...
         if isinstance(installer, Copr):