diff --git a/lib/galaxy/tool_util/loader_directory.py b/lib/galaxy/tool_util/loader_directory.py
index fd0e73e58f5b..1491f5ab047a 100644
--- a/lib/galaxy/tool_util/loader_directory.py
+++ b/lib/galaxy/tool_util/loader_directory.py
@@ -190,7 +190,7 @@ def looks_like_a_data_manager_xml(path):
 
 def as_dict_if_looks_like_yaml_or_cwl_with_class(path, classes):
     """
-    get a dict from yaml file if it contains `class: CLASS`, where CLASS is
+    get a dict from yaml file if it contains a line `class: CLASS`, where CLASS is
     any string given in CLASSES. must appear in the first 5k and also load
     properly in total.
     """
@@ -199,7 +199,7 @@ def as_dict_if_looks_like_yaml_or_cwl_with_class(path, classes):
             start_contents = f.read(5 * 1024)
         except UnicodeDecodeError:
             return False, None
-        if re.search(rf"\nclass:\s+({'|'.join(classes)})\s*\n", start_contents) is None:
+        if re.search(rf"^class:\s+{'|'.join(classes)}\s*$", start_contents, re.MULTILINE) is None:
             return False, None
 
     with open(path) as f:
diff --git a/test/unit/tool_util/test_loader_directory.py b/test/unit/tool_util/test_loader_directory.py
new file mode 100644
index 000000000000..08ec1f5a51c1
--- /dev/null
+++ b/test/unit/tool_util/test_loader_directory.py
@@ -0,0 +1,24 @@
+import tempfile
+
+from galaxy.tool_util.loader_directory import is_a_yaml_with_class
+
+
+def test_is_a_yaml_with_class():
+    with tempfile.NamedTemporaryFile("w", suffix=".yaml") as tf:
+        fname = tf.name
+        tf.write(
+            """class: GalaxyWorkflow
+name: "Test Workflow"
+inputs:
+  - id: input1
+outputs:
+  - id: wf_output_1
+    outputSource: first_cat/out_file1
+steps:
+  - tool_id: cat
+    label: first_cat
+    in:
+      input1: input1"""
+        )
+        tf.flush()
+        assert is_a_yaml_with_class(fname, ["GalaxyWorkflow"])