matplotlib
diff --git a/‎lib/matplotlib/collections.py‎
Lines changed: 7 additions & 12 deletions b/‎lib/matplotlib/collections.py‎
Lines changed: 7 additions & 12 deletions
diff --git a/‎lib/matplotlib/tests/test_collections.py‎
Lines changed: 6 additions & 0 deletions b/‎lib/matplotlib/tests/test_collections.py‎
Lines changed: 6 additions & 0 deletions
@@ -608,18 +608,13 @@ def set_linestyle(self, ls):
             complete description.
         """
         try:
-            if isinstance(ls, str):
-                ls = cbook.ls_mapper.get(ls, ls)
-                dashes = [mlines._get_dash_pattern(ls)]
-            else:
-                try:
-                    dashes = [mlines._get_dash_pattern(ls)]
-                except ValueError:
-                    dashes = [mlines._get_dash_pattern(x) for x in ls]
-
-        except ValueError as err:
-            raise ValueError('Do not know how to convert {!r} to '
-                             'dashes'.format(ls)) from err
+            dashes = [mlines._get_dash_pattern(ls)]
+        except ValueError:
+            try:
+                dashes = [mlines._get_dash_pattern(x) for x in ls]
+            except ValueError as err:
+                emsg = f'Do not know how to convert {ls!r} to dashes'
+                raise ValueError(emsg) from err
 
         # get the list of raw 'unscaled' dash patterns
         self._us_linestyles = dashes
 
@@ -611,6 +611,12 @@ def test_lslw_bcast():
     assert (col.get_linewidths() == [1, 2, 3]).all()
 
 
+def test_set_wrong_linestyle():
+    c = Collection()
+    with pytest.raises(ValueError, match="Do not know how to convert 'fuzzy'"):
+        c.set_linestyle('fuzzy')
+
+
 @mpl.style.context('default')
 def test_capstyle():
     col = mcollections.PathCollection([], capstyle='round')