diff --git a/scripts/acceptance.bats b/scripts/acceptance.bats
index c210d45..4398c4e 100644
--- a/scripts/acceptance.bats
+++ b/scripts/acceptance.bats
@@ -72,3 +72,10 @@ setup() {
   run diff prometheus_v1.json ./fixtures/prometheus_v1-denyRootAdditionalProperties.json
   [ "$status" -eq 0 ]
 }
+
+@test "Should output an error if no file is passed" {
+  run ./openapi2jsonschema.py
+  [ "$status" -eq 1 ]
+  [ "${lines[0]}" == 'Missing FILE parameter.' ]
+  [ "${lines[1]}" == 'Usage: ./openapi2jsonschema.py [FILE]' ]
+}
diff --git a/scripts/openapi2jsonschema.py b/scripts/openapi2jsonschema.py
index 9d981b4..6cda017 100755
--- a/scripts/openapi2jsonschema.py
+++ b/scripts/openapi2jsonschema.py
@@ -122,8 +122,8 @@ def construct_value(load, node):
 
 
 if __name__ == "__main__":
-  if len(sys.argv) == 0:
-      print("missing file")
+  if len(sys.argv) < 2:
+      print('Missing FILE parameter.\nUsage: %s [FILE]' % sys.argv[0])
       exit(1)
 
   for crdFile in sys.argv[1:]: