diff --git a/packages/python/plotly/plotly/tests/test_core/test_validators/__init__.py b/packages/python/plotly/plotly/tests/test_core/test_validators/__init__.py
new file mode 100644
index 00000000000..e1565c83f71
--- /dev/null
+++ b/packages/python/plotly/plotly/tests/test_core/test_validators/__init__.py
@@ -0,0 +1,5 @@
+import warnings
+
+
+def setup_package():
+    warnings.filterwarnings("ignore")
diff --git a/packages/python/plotly/plotly/tests/test_core/test_validators/test_validators.py b/packages/python/plotly/plotly/tests/test_core/test_validators/test_validators.py
new file mode 100644
index 00000000000..855a47a4d9d
--- /dev/null
+++ b/packages/python/plotly/plotly/tests/test_core/test_validators/test_validators.py
@@ -0,0 +1,11 @@
+
+from __future__ import absolute_import
+
+from unittest import TestCase
+import plotly.graph_objs as go
+
+
+class TestValidators(TestCase):
+    def test_layout_shape_line_dash_validator(self):
+        # regression from issue #3375
+        go.layout.shape.Line(color='black', width=2, dash='5px,3px,3px,2px')
diff --git a/packages/python/plotly/plotly/validators/layout/shape/line/_dash.py b/packages/python/plotly/plotly/validators/layout/shape/line/_dash.py
index 4b42018c816..77766d5540b 100644
--- a/packages/python/plotly/plotly/validators/layout/shape/line/_dash.py
+++ b/packages/python/plotly/plotly/validators/layout/shape/line/_dash.py
@@ -1,7 +1,7 @@
 import _plotly_utils.basevalidators
 
 
-class DashValidator(_plotly_utils.basevalidators.StringValidator):
+class DashValidator(_plotly_utils.basevalidators.DashValidator):
     def __init__(self, plotly_name="dash", parent_name="layout.shape.line", **kwargs):
         super(DashValidator, self).__init__(
             plotly_name=plotly_name,