diff --git a/cranelift/codegen/shared/src/isa/x86/encoding_bits.rs b/cranelift/codegen/shared/src/isa/x86/encoding_bits.rs
index ba6418f7cf..9edb2a6e6f 100644
--- a/cranelift/codegen/shared/src/isa/x86/encoding_bits.rs
+++ b/cranelift/codegen/shared/src/isa/x86/encoding_bits.rs
@@ -59,20 +59,18 @@ impl EncodingBits {
 
     /// Returns a copy of the EncodingBits with the RRR bits set.
     #[inline]
-    pub fn with_rrr(self, rrr: u8) -> Self {
-        debug_assert_eq!(u8::from(self.rrr()), 0);
-        let mut enc = self.clone();
-        enc.write(RRR, rrr.into());
-        enc
+    pub fn with_rrr(mut self, rrr: u8) -> Self {
+        debug_assert_eq!(self.rrr(), 0);
+        self.write(RRR, rrr.into());
+        self
     }
 
     /// Returns a copy of the EncodingBits with the REX.W bit set.
     #[inline]
-    pub fn with_rex_w(self) -> Self {
+    pub fn with_rex_w(mut self) -> Self {
         debug_assert_eq!(self.rex_w(), 0);
-        let mut enc = self.clone();
-        enc.write(REX_W, 1);
-        enc
+        self.write(REX_W, 1);
+        self
     }
 
     /// Returns the raw bits.