diff --git a/.github/workflows/unit_tests.yml b/.github/workflows/unit_tests.yml
index b8f4734d..338941ec 100644
--- a/.github/workflows/unit_tests.yml
+++ b/.github/workflows/unit_tests.yml
@@ -22,3 +22,5 @@ jobs:
         run: pip install tox
       - name: Run Tox
         run: tox -e py
+      - name: Run Tox Flask 1
+        run: tox -e flask1
diff --git a/flask_jwt_extended/view_decorators.py b/flask_jwt_extended/view_decorators.py
index f3ba655e..9defc595 100644
--- a/flask_jwt_extended/view_decorators.py
+++ b/flask_jwt_extended/view_decorators.py
@@ -121,12 +121,12 @@ def decorator(*args, **kwargs):
             verify_jwt_in_request(optional, fresh, refresh, locations)
 
             # Compatibility with flask < 2.0
-            try:
+            if hasattr(current_app, "ensure_sync") and callable(
+                getattr(current_app, "ensure_sync", None)
+            ):
                 return current_app.ensure_sync(fn)(*args, **kwargs)
-            except AttributeError as e:  # pragma: no cover
-                if str(e) != "'Flask' object has no attribute 'ensure_sync'":
-                    raise
-                return fn(*args, **kwargs)
+
+            return fn(*args, **kwargs)  # pragma: no cover
 
         return decorator
 
diff --git a/tox.ini b/tox.ini
index a9b46292..a0d5f940 100644
--- a/tox.ini
+++ b/tox.ini
@@ -4,7 +4,7 @@
 # and then run "tox" from this directory.
 
 [tox]
-envlist = py36,py37,py38,py39,pypy3,coverage,style,docs
+envlist = py36,py37,py38,py39,pypy3,flask1,coverage,style,docs
 
 [testenv]
 commands =
@@ -13,6 +13,7 @@ deps =
   pytest
   cryptography
   python-dateutil
+  flask1: flask == 1.1.4
 
 [testenv:coverage]
 commands =