Index: src/OFFloatMatrix.m
==================================================================
--- src/OFFloatMatrix.m
+++ src/OFFloatMatrix.m
@@ -170,11 +170,11 @@
 
 - (BOOL)isEqual: (id)object
 {
 	OFFloatMatrix *otherMatrix;
 
-	if (object->isa != isa)
+	if (![object isKindOfClass: [OFFloatMatrix class]])
 		return NO;
 
 	otherMatrix = object;
 
 	if (otherMatrix->rows != rows || otherMatrix->columns != columns)

Index: src/OFFloatVector.m
==================================================================
--- src/OFFloatVector.m
+++ src/OFFloatVector.m
@@ -134,11 +134,11 @@
 
 - (BOOL)isEqual: (id)object
 {
 	OFFloatVector *otherVector;
 
-	if (object->isa != isa)
+	if (![object isKindOfClass: [OFFloatVector class]])
 		return NO;
 
 	otherVector = object;
 
 	if (otherVector->dimension != dimension)