diff --git a/Source/OCMock/OCMInvocationMatcher.m b/Source/OCMock/OCMInvocationMatcher.m
index 035e0241..340802bb 100644
--- a/Source/OCMock/OCMInvocationMatcher.m
+++ b/Source/OCMock/OCMInvocationMatcher.m
@@ -89,8 +89,8 @@ - (BOOL)matchesInvocation:(NSInvocation *)anInvocation
         return NO;
 
     NSMethodSignature *signature = [recordedInvocation methodSignature];
-    int n = (int)[signature numberOfArguments];
-    for(int i = 2; i < n; i++)
+    NSUInteger n = [signature numberOfArguments];
+    for(NSUInteger i = 2; i < n; i++)
     {
         if(ignoreNonObjectArgs && strcmp([signature getArgumentTypeAtIndex:i], @encode(id)))
         {