diff --git a/planemo/shed_lint.py b/planemo/shed_lint.py
index b34a1e04e..7517b4bc8 100644
--- a/planemo/shed_lint.py
+++ b/planemo/shed_lint.py
@@ -290,14 +290,14 @@ def lint_repository_dependencies(realized_repository, lint_ctx):
 def lint_shed_yaml(realized_repository, lint_ctx):
     path = realized_repository.real_path
     shed_yaml = os.path.join(path, ".shed.yml")
-    if not os.path.exists(shed_yaml):
-        lint_ctx.info("No .shed.yml file found, skipping.")
+    if not os.path.exists(shed_yaml) and realized_repository.repository_type != REPO_TYPE_UNRESTRICTED:
+        lint_ctx.error("No .shed.yml file found, skipping.")
         return
     try:
         with open(shed_yaml, "r") as fh:
             yaml.safe_load(fh)
     except Exception as e:
-        lint_ctx.warn("Failed to parse .shed.yml file [%s]" % unicodify(e))
+        lint_ctx.error("Failed to parse .shed.yml file [%s]" % unicodify(e))
         return
     lint_ctx.info(".shed.yml found and appears to be valid YAML.")
     _lint_shed_contents(lint_ctx, realized_repository)
@@ -311,12 +311,17 @@ def _lint_if_present(key, func, *args):
         if value is not None:
             msg = func(value, *args)
             if msg:
-                lint_ctx.warn(msg)
+                lint_ctx.error(msg)
+        return value
 
-    _lint_if_present("owner", validate_repo_owner)
-    _lint_if_present("name", validate_repo_name)
+    def _lint(key, func, *args):
+        if _lint_if_present(key, func, *args) is None:
+            lint_ctx.error("Repository does not define: %s" % key)
+
+    _lint("owner", validate_repo_owner)
+    _lint("name", validate_repo_name)
     _lint_if_present("type", _validate_repo_type, config["name"])
-    _lint_if_present("categories", _validate_categories, realized_repository)
+    _lint("categories", _validate_categories, realized_repository)
 
 
 def _validate_repo_type(repo_type, name):
diff --git a/tests/data/repos/bad_invalid_tool_xml/.shed.yml b/tests/data/repos/bad_invalid_tool_xml/.shed.yml
new file mode 100644
index 000000000..e439fa5f3
--- /dev/null
+++ b/tests/data/repos/bad_invalid_tool_xml/.shed.yml
@@ -0,0 +1,5 @@
+name: cat
+owner: iuc
+description: cat1 tool
+categories:
+- Text Manipulation
diff --git a/tests/data/repos/multi_repos_nested/cat1/.shed.yml b/tests/data/repos/multi_repos_nested/cat1/.shed.yml
index 4953b136e..3a2a1996d 100644
--- a/tests/data/repos/multi_repos_nested/cat1/.shed.yml
+++ b/tests/data/repos/multi_repos_nested/cat1/.shed.yml
@@ -1,3 +1,5 @@
 name: cat1
 owner: iuc
 description: cat1 tool
+categories:
+- Text Manipulation
diff --git a/tests/data/repos/multi_repos_nested/cat2/.shed.yml b/tests/data/repos/multi_repos_nested/cat2/.shed.yml
index a87f516a5..f5e39e3c9 100644
--- a/tests/data/repos/multi_repos_nested/cat2/.shed.yml
+++ b/tests/data/repos/multi_repos_nested/cat2/.shed.yml
@@ -1,3 +1,5 @@
 name: cat2
 owner: iuc
 description: cat2 tool
+categories:
+- Text Manipulation