diff --git a/src/lib.rs b/src/lib.rs
index 17273fe..1b7e111 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -18,7 +18,7 @@ macro_rules! format_args {
 
 pub use crate::{
     args::{pub_exports::*, Arguments},
-    formatter::Formatter,
+    formatter::{DebugList, DebugMap, DebugSet, DebugStruct, DebugTuple, Formatter},
     opts::FmtOpts,
 };
 
@@ -114,3 +114,10 @@ mod tests {
         assert_eq!(result, "a: {6}");
     }
 }
+
+pub mod uwu {
+    fn test_format_debug_hex() {
+        assert_eq!(format!("{:02x?}", b"Foo\0"), "[46, 6f, 6f, 00]");
+        assert_eq!(format!("{:02X?}", b"Foo\0"), "[46, 6F, 6F, 00]");
+    }
+}
diff --git a/src/opts.rs b/src/opts.rs
index 2266aa9..760c422 100644
--- a/src/opts.rs
+++ b/src/opts.rs
@@ -165,5 +165,5 @@ options!(
     struct WithDebugLowerHex { true }
 
     fn debug_upper_hex(&self) -> bool { false }
-    struct WithDebugUpperHex { false }
+    struct WithDebugUpperHex { true }
 );
diff --git a/src/write.rs b/src/write.rs
index b5a0631..ac27f9c 100644
--- a/src/write.rs
+++ b/src/write.rs
@@ -1,4 +1,4 @@
-use crate::{Result, Write};
+use crate::{Error, Result, Write};
 
 impl<W: Write> Write for &mut W {
     fn write_str(&mut self, str: &str) -> Result {
@@ -10,12 +10,21 @@ impl<W: Write> Write for &mut W {
     }
 }
 
+/// Write is implemented for `&mut [u8]` by copying into the slice, overwriting
+/// its data.
+///
+/// Note that writing updates the slice to point to the yet unwritten part.
+/// The slice will be empty when it has been completely overwritten.
 impl Write for &'_ mut [u8] {
     fn write_str(&mut self, str: &str) -> Result {
         let data = str.as_bytes();
-        let amt = core::cmp::min(str.len(), self.len());
-        let (a, b) = core::mem::replace(self, &mut []).split_at_mut(amt);
-        a.copy_from_slice(&data[..amt]);
+
+        if data.len() > self.len() {
+            return Err(Error);
+        }
+
+        let (a, b) = core::mem::replace(self, &mut []).split_at_mut(data.len());
+        a.copy_from_slice(data);
         *self = b;
         Ok(())
     }
@@ -72,25 +81,23 @@ mod std_impls {
         net, process,
     };
 
-    use crate::Result;
-
-    trait IoWriteForwad: IoWrite {
-        fn write_str(&mut self, str: &str) -> Result {
-            <Self as IoWrite>::write_all(self, str.as_bytes()).map_err(|_| crate::Error)
-        }
-
-        fn write_char(&mut self, char: char) -> Result {
-            let mut buf = [0; 4];
-
-            <Self as IoWrite>::write_all(self, char.encode_utf8(&mut buf).as_bytes())
-                .map_err(|_| crate::Error)
-        }
-    }
+    use crate::{Result, Write};
 
     macro_rules! impl_io_forward {
         ($($name:ty),* $(,)?) => {
             $(
-                impl IoWriteForwad for $name {}
+                impl Write for $name {
+                    fn write_str(&mut self, str: &str) -> Result {
+                        <Self as IoWrite>::write_all(self, str.as_bytes()).map_err(|_| crate::Error)
+                    }
+
+                    fn write_char(&mut self, char: char) -> Result {
+                        let mut buf = [0; 4];
+
+                        <Self as IoWrite>::write_all(self, char.encode_utf8(&mut buf).as_bytes())
+                            .map_err(|_| crate::Error)
+                    }
+                }
             )*
         };
     }