diff --git a/src/memory.rs b/src/memory.rs
index 5794dc783cf..638a8d2ff27 100644
--- a/src/memory.rs
+++ b/src/memory.rs
@@ -772,7 +772,7 @@ impl<'a, 'tcx> Memory<'a, 'tcx> {
                     4 => !0u32 as u128,
                     8 => !0u64 as u128,
                     16 => !0,
-                    _ => bug!("unexpected PrimVal::Bytes size"),
+                    n => bug!("unexpected PrimVal::Bytes size: {}", n),
                 };
                 self.write_uint(dest.to_ptr()?, bytes & mask, size)
             }
diff --git a/src/value.rs b/src/value.rs
index 85f79b7831e..90278d63e7f 100644
--- a/src/value.rs
+++ b/src/value.rs
@@ -108,7 +108,7 @@ impl<'a, 'tcx: 'a> Value {
                 assert_eq!(len as u64 as u128, len);
                 Ok((ptr, len as u64))
             },
-            _ => unimplemented!(),
+            ByVal(_) => unimplemented!(),
         }
     }
 }