diff --git a/Lib/fontParts/base/base.py b/Lib/fontParts/base/base.py
index 6172c128..a0b6da74 100644
--- a/Lib/fontParts/base/base.py
+++ b/Lib/fontParts/base/base.py
@@ -241,8 +241,7 @@ def __repr__(self) -> str:
             contentString = ""
         return f"<{self.__class__.__name__}{contentString} at {id(self)}>"
 
-    @classmethod
-    def _reprContents(cls) -> List[str]:
+    def _reprContents(self) -> List[str]:
         """Provide a list of strings for inclusion in :meth:`BaseObject.__repr__.
 
         :return: A :class:`list` of :class:`str` items.
diff --git a/Lib/fontParts/base/component.py b/Lib/fontParts/base/component.py
index c65d4cec..14f584bf 100644
--- a/Lib/fontParts/base/component.py
+++ b/Lib/fontParts/base/component.py
@@ -628,7 +628,7 @@ def _decompose(self) -> None:
     compatibilityReporterClass = ComponentCompatibilityReporter
 
     def isCompatible(
-        self, other: BaseComponent
+        self, other: BaseComponent, cls=None
     ) -> Tuple[bool, ComponentCompatibilityReporter]:
         """Evaluate interpolation compatibility with another component.
 
diff --git a/Lib/fontParts/base/contour.py b/Lib/fontParts/base/contour.py
index 8d513f5f..041bea4a 100644
--- a/Lib/fontParts/base/contour.py
+++ b/Lib/fontParts/base/contour.py
@@ -488,7 +488,7 @@ def _transformBy(
     compatibilityReporterClass = ContourCompatibilityReporter
 
     def isCompatible(
-        self, other: BaseContour
+        self, other: BaseContour, cls=None
     ) -> Tuple[bool, ContourCompatibilityReporter]:
         """Evaluate interpolation compatibility with another contour.
 
diff --git a/Lib/fontParts/base/font.py b/Lib/fontParts/base/font.py
index 37f67ca8..75002d68 100644
--- a/Lib/fontParts/base/font.py
+++ b/Lib/fontParts/base/font.py
@@ -2058,7 +2058,9 @@ def _interpolate(
 
     compatibilityReporterClass = FontCompatibilityReporter
 
-    def isCompatible(self, other: BaseFont) -> Tuple[bool, FontCompatibilityReporter]:
+    def isCompatible(
+        self, other: BaseFont, cls=None
+    ) -> Tuple[bool, FontCompatibilityReporter]:
         """Evaluate interpolation compatibility with another font.
 
         This method will return a :class:`bool` indicating if the font is
diff --git a/Lib/fontParts/base/glyph.py b/Lib/fontParts/base/glyph.py
index 13b02a7a..dc6c9a81 100644
--- a/Lib/fontParts/base/glyph.py
+++ b/Lib/fontParts/base/glyph.py
@@ -2795,7 +2795,9 @@ def _checkPairs(
                 reporter.warning = True
             reporterObject.append(compatibility)
 
-    def isCompatible(self, other: BaseGlyph) -> Tuple[bool, GlyphCompatibilityReporter]:
+    def isCompatible(
+        self, other: BaseGlyph, cls=None
+    ) -> Tuple[bool, GlyphCompatibilityReporter]:
         """Evaluate interpolation compatibility with another glyph.
 
         :param other: The other :class:`BaseGlyph` instance to check
diff --git a/Lib/fontParts/base/layer.py b/Lib/fontParts/base/layer.py
index 6b008105..081e81eb 100644
--- a/Lib/fontParts/base/layer.py
+++ b/Lib/fontParts/base/layer.py
@@ -1106,7 +1106,9 @@ def _interpolate(
 
     compatibilityReporterClass = LayerCompatibilityReporter
 
-    def isCompatible(self, other: BaseLayer) -> Tuple[bool, LayerCompatibilityReporter]:
+    def isCompatible(
+        self, other: BaseLayer, cls=None
+    ) -> Tuple[bool, LayerCompatibilityReporter]:
         """Evaluate interpolation compatibility with another layer.
 
         :param other: The other :class:`BaseLayer` instance to check
diff --git a/Lib/fontParts/base/segment.py b/Lib/fontParts/base/segment.py
index d0267513..5737c581 100644
--- a/Lib/fontParts/base/segment.py
+++ b/Lib/fontParts/base/segment.py
@@ -614,7 +614,7 @@ def _transformBy(self, matrix: SextupleCollectionType[IntFloatType], **kwargs: A
     compatibilityReporterClass = SegmentCompatibilityReporter
 
     def isCompatible(
-        self, other: BaseSegment
+        self, other: BaseSegment, cls=None
     ) -> Tuple[bool, SegmentCompatibilityReporter]:
         """Evaluate interpolation compatibility with another segment.