diff --git a/Code/ObjectMapping/RKObjectMapper.m b/Code/ObjectMapping/RKObjectMapper.m
index 13a7215c..18a20067 100644
--- a/Code/ObjectMapping/RKObjectMapper.m
+++ b/Code/ObjectMapping/RKObjectMapper.m
@@ -202,7 +202,7 @@
 }
 
 // The workhorse of this entire process. Emits object loading operations
-- (BOOL)mapFromObject:(id)mappableObject toObject:(id)destinationObject atKeyPath:keyPath usingMapping:(id<RKObjectMappingDefinition>)mapping {
+- (BOOL)mapFromObject:(id)mappableObject toObject:(id)destinationObject atKeyPath:(NSString *)keyPath usingMapping:(id<RKObjectMappingDefinition>)mapping {
     NSAssert(destinationObject != nil, @"Cannot map without a target object to assign the results to");    
     NSAssert(mappableObject != nil, @"Cannot map without a collection of attributes");
     NSAssert(mapping != nil, @"Cannot map without an mapping");
diff --git a/Code/ObjectMapping/RKObjectMapper_Private.h b/Code/ObjectMapping/RKObjectMapper_Private.h
index 21c066de..66b71a31 100644
--- a/Code/ObjectMapping/RKObjectMapper_Private.h
+++ b/Code/ObjectMapping/RKObjectMapper_Private.h
@@ -20,9 +20,9 @@
 
 @interface RKObjectMapper (Private)
 
-- (id)mapObject:(id)mappableObject atKeyPath:keyPath usingMapping:(id<RKObjectMappingDefinition>)mapping;
+- (id)mapObject:(id)mappableObject atKeyPath:(NSString *)keyPath usingMapping:(id<RKObjectMappingDefinition>)mapping;
 - (NSArray*)mapCollection:(NSArray*)mappableObjects atKeyPath:(NSString*)keyPath usingMapping:(id<RKObjectMappingDefinition>)mapping;
-- (BOOL)mapFromObject:(id)mappableObject toObject:(id)destinationObject atKeyPath:keyPath usingMapping:(id<RKObjectMappingDefinition>)mapping;
+- (BOOL)mapFromObject:(id)mappableObject toObject:(id)destinationObject atKeyPath:(NSString *)keyPath usingMapping:(id<RKObjectMappingDefinition>)mapping;
 - (id)objectWithMapping:(id<RKObjectMappingDefinition>)objectMapping andData:(id)mappableData;
 
 @end
diff --git a/Code/ObjectMapping/RKObjectMappingOperation.m b/Code/ObjectMapping/RKObjectMappingOperation.m
index 99f02994..12dd841b 100644
--- a/Code/ObjectMapping/RKObjectMappingOperation.m
+++ b/Code/ObjectMapping/RKObjectMappingOperation.m
@@ -139,7 +139,7 @@ BOOL RKObjectIsValueEqualToValue(id sourceValue, id destinationValue) {
     return date;
 }
 
-- (id)transformValue:(id)value atKeyPath:keyPath toType:(Class)destinationType {
+- (id)transformValue:(id)value atKeyPath:(NSString *)keyPath toType:(Class)destinationType {
     RKLogTrace(@"Found transformable value at keyPath '%@'. Transforming from type '%@' to '%@'", keyPath, NSStringFromClass([value class]), NSStringFromClass(destinationType));
     Class sourceType = [value class];