diff --git a/src/scanspec/core.py b/src/scanspec/core.py
index cd39fb1c..f071720c 100644
--- a/src/scanspec/core.py
+++ b/src/scanspec/core.py
@@ -337,9 +337,9 @@ def concat(self, other: Frames[Axis], gap: bool = False) -> Frames[Axis]:
         {'x': array([1, 2, 3, 4, 5, 6]), 'y': array([6, 5, 4, 3, 2, 1])}
 
         """
-        assert set(self.axes()) == set(
-            other.axes()
-        ), f"axes {self.axes()} != {other.axes()}"
+        assert set(self.axes()) == set(other.axes()), (
+            f"axes {self.axes()} != {other.axes()}"
+        )
 
         def concat_dict(ds: Sequence[AxesPoints[Axis]]) -> AxesPoints[Axis]:
             # Concat each array in midpoints, lower, upper. E.g.
diff --git a/src/scanspec/specs.py b/src/scanspec/specs.py
index 5a7807e9..3f4bd0c8 100644
--- a/src/scanspec/specs.py
+++ b/src/scanspec/specs.py
@@ -234,9 +234,9 @@ def calculate(  # noqa: D102
     ) -> list[Frames[Axis]]:
         frames_left = self.left.calculate(bounds, nested)
         frames_right = self.right.calculate(bounds, nested)
-        assert len(frames_left) >= len(
-            frames_right
-        ), f"Zip requires len({self.left}) >= len({self.right})"
+        assert len(frames_left) >= len(frames_right), (
+            f"Zip requires len({self.left}) >= len({self.right})"
+        )
 
         # Pad and expand the right to be the same size as left. Special case, if
         # only one Frames object with size 1, expand to the right size
@@ -262,9 +262,9 @@ def calculate(  # noqa: D102
                 combined = left
             else:
                 combined = left.zip(right)
-            assert isinstance(
-                combined, Frames
-            ), f"Padding went wrong {frames_left} {padded_right}"
+            assert isinstance(combined, Frames), (
+                f"Padding went wrong {frames_left} {padded_right}"
+            )
             frames.append(combined)
         return frames