diff --git a/main_test.go b/main_test.go
index 6b3a914..86f1b1f 100644
--- a/main_test.go
+++ b/main_test.go
@@ -134,6 +134,7 @@ func TestApi(t *testing.T) {
 func TestValidateEndpoint(t *testing.T) {
 	validYml := loadTestdata(t, "valid.publiccode.yml")
 	invalidYml := loadTestdata(t, "invalid.publiccode.yml")
+	malformedYml := loadTestdata(t, "malformed.publiccode.yml")
 	externalChecksYml := strings.Replace(
 		validYml,
 		"https://github.com/example/project.git",
@@ -248,6 +249,20 @@ func TestValidateEndpoint(t *testing.T) {
 				assert.Nil(t, response["normalized"])
 			},
 		},
+		{
+			description:         "validate: malformed YAML",
+			query:               "QUERY /v1/validate",
+			body:                malformedYml,
+			expectedCode:        200,
+			expectedContentType: "application/json; charset=utf-8",
+			validateFunc: func(t *testing.T, response map[string]any) {
+				assert.Equal(t, false, response["valid"])
+				results, ok := response["results"].([]any)
+				assert.True(t, ok)
+				assert.NotEmpty(t, results)
+				assert.Nil(t, response["normalized"])
+			},
+		},
 	}
 
 	runTestCases(t, tests)
diff --git a/testdata/malformed.publiccode.yml b/testdata/malformed.publiccode.yml
new file mode 100644
index 0000000..3d31616
--- /dev/null
+++ b/testdata/malformed.publiccode.yml
@@ -0,0 +1,2 @@
+publiccodeYmlVersion: "0"
+name: [unterminated