diff --git a/src/data.rs b/src/data.rs
index db898d8..91093b7 100644
--- a/src/data.rs
+++ b/src/data.rs
@@ -84,3 +84,7 @@ mod pointer_iterator {
 pub fn iterate<T: pointer_iterator::Pointer>(pointer: T) -> T::IterType {
     pointer.into_iter()
 }
+
+pub fn fill_with<T, F: FnMut(usize) -> T>(slice: &mut [T], mut func: F) {
+    slice.iter_mut().enumerate().for_each(|(i,v)|*v = func(i))
+}
\ No newline at end of file
diff --git a/src/lib.rs b/src/lib.rs
index d9d7199..b6d8532 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -32,7 +32,6 @@ pub mod win32;
 #[cfg(feature = "win32")]
 pub use win32::{ image_base, image_header, find_kernel32, process_executable };
 
-
 /// re-export the signature macro
 pub use xgen::signature;
 
diff --git a/src/upcast.rs b/src/upcast.rs
index aa35d55..b2e25fc 100644
--- a/src/upcast.rs
+++ b/src/upcast.rs
@@ -50,9 +50,13 @@ gen_upcast!(i16     => isize);
 
 #[cfg(any(target_pointer_width = "64", target_pointer_width = "32"))]
 gen_upcast!(u32     => usize);
+#[cfg(any(target_pointer_width = "64"))]
+gen_upcast!(u64     => usize);
 
 #[cfg(any(target_pointer_width = "64", target_pointer_width = "32"))]
 gen_upcast!(i32     => isize);
+#[cfg(any(target_pointer_width = "64"))]
+gen_upcast!(i64     => isize);
 
 gen_upcast!(isize   => isize);
 gen_upcast!(usize   => usize);