Aright, what’s up with this? This code using a double works just fine: double myDouble = 2.2; NSLog(@"myDouble %f", myDouble); [self testDouble:myDouble]; - (void) testDouble:(double)myDouble { NSLog(@"testDouble %f", myDouble); } This code prints: myDouble 2.200000 testDouble 2.200000 No surprises there. But the same code using a float behaves very strangely: float myFloat = 3.3; NSLog(@"myFloat [...]