diff --git a/.github/workflows/test.yml b/.github/workflows/test.yml
index 0b2cb64c..56910edb 100644
--- a/.github/workflows/test.yml
+++ b/.github/workflows/test.yml
@@ -1,6 +1,6 @@
 name: test
 
-on: [ push ]
+on: [ push, pull_request ]
 
 concurrency:
   group: test-${{ github.head_ref }}
@@ -19,18 +19,20 @@ jobs:
     strategy:
       matrix:
         python-version: [3.8, 3.9, "3.10", 3.11, 3.12]
-        django-version: [4.2, 5.0, "main"]
+        django-version: [4.2, 5.0, 5.1, "main"]
         exclude:
-            # Django 4.2
-            - python-version: 3.12
-              django-version: 4.2
-
             # Django 5.0
             - python-version: 3.8
               django-version: 5.0
             - python-version: 3.9
               django-version: 5.0
 
+            # Django 5.1
+            - python-version: 3.8
+              django-version: 5.1
+            - python-version: 3.9
+              django-version: 5.1
+
             # Django main
             - python-version: 3.8
               django-version: "main"
diff --git a/example/app/views.py b/example/app/views.py
index 8b0a0b50..1e7d290e 100644
--- a/example/app/views.py
+++ b/example/app/views.py
@@ -70,7 +70,7 @@ def get_context_data(self, **kwargs):
         context = super().get_context_data(**kwargs)
         lines = []
         for i in range(200):
-            lines.append("Line %s" % (i + 1))
+            lines.append(f"Line {i + 1}")
         paginator = Paginator(lines, 10)
         page = self.request.GET.get("page")
         try:
diff --git a/src/bootstrap4/renderers.py b/src/bootstrap4/renderers.py
index dda3fcb6..93f18bb6 100644
--- a/src/bootstrap4/renderers.py
+++ b/src/bootstrap4/renderers.py
@@ -69,7 +69,7 @@ def parse_size(self, size):
             return "large"
         if size in ("md", "medium", ""):
             return "medium"
-        raise BootstrapError('Invalid value "%s" for parameter "size" (expected "sm", "md", "lg" or "").' % size)
+        raise BootstrapError(f'Invalid value "{size}" for parameter "size" (expected "sm", "md", "lg" or "").')
 
     def get_size_class(self, prefix="form-control"):
         if self.size == "small":
diff --git a/tests/test_formsets.py b/tests/test_formsets.py
index 0f8b2bc0..86791791 100644
--- a/tests/test_formsets.py
+++ b/tests/test_formsets.py
@@ -27,7 +27,7 @@ def test_field_names(self):
                 self.assertIn('name="datetime_0"', res)
                 self.assertIn('name="datetime_1"', res)
             else:
-                self.assertIn('name="%s"' % field.name, res)
+                self.assertIn(f'name="{field.name}"', res)
 
     def test_field_addons(self):
         form = TestForm()
diff --git a/tests/utils.py b/tests/utils.py
index 53d0110c..3bd2c3e1 100644
--- a/tests/utils.py
+++ b/tests/utils.py
@@ -39,7 +39,7 @@ def render_form(form=None, context=None):
 
 def render_form_field(field, context=None):
     """Create a template that renders a field."""
-    form_field = "form.%s" % field
+    form_field = f"form.{field}"
     return render_template_with_form("{% bootstrap_field " + form_field + " %}", context)
 
 
diff --git a/tox.ini b/tox.ini
index 94b9eee6..b40bc702 100644
--- a/tox.ini
+++ b/tox.ini
@@ -3,9 +3,9 @@ args_are_paths = false
 envlist =
     py38-{4.2},
     py39-{4.2},
-    py310-{4.2,5.0,main},
-    py311-{4.2,5.0,main},
-    py312-{4.2,5.0,main},
+    py310-{4.2,5.0,5.1,main},
+    py311-{4.2,5.0,5.1,main},
+    py312-{4.2,5.0,5.1,main},
     docs,
     lint,
 
@@ -26,6 +26,7 @@ commands =
 deps =
     4.2: Django==4.2.*
     5.0: Django==5.0.*
+    5.1: Django==5.1.*
     main: https://github.com/django/django/archive/main.tar.gz
     -r{toxinidir}/requirements-test.txt