diff --git a/src/librustc/ty/print/pretty.rs b/src/librustc/ty/print/pretty.rs
index 446bb3db0046..76503eb10fcf 100644
--- a/src/librustc/ty/print/pretty.rs
+++ b/src/librustc/ty/print/pretty.rs
@@ -988,9 +988,9 @@ pub trait PrettyPrinter<'tcx>:
             // For zsts just print their type as their value gives no extra information
             (Scalar::Raw { size: 0, .. }, _) => p!(print(ty)),
             // Nontrivial types with scalar bit representation
-            (Scalar::Raw { data, .. }, _) => {
+            (Scalar::Raw { data, size }, _) => {
                 let print = |mut this: Self| {
-                    write!(this, "transmute(0x{:x})", data)?;
+                    write!(this, "transmute(0x{:01$x})", data, size as usize * 2)?;
                     Ok(this)
                 };
                 self = if print_ty {
diff --git a/src/test/mir-opt/const_prop/discriminant.rs b/src/test/mir-opt/const_prop/discriminant.rs
index 587f81f7f879..636aa1af6533 100644
--- a/src/test/mir-opt/const_prop/discriminant.rs
+++ b/src/test/mir-opt/const_prop/discriminant.rs
@@ -31,7 +31,7 @@ fn main() {
 // START rustc.main.ConstProp.after.mir
 //  bb0: {
 //      ...
-//      _3 = const {transmute(0x1): std::option::Option<bool>};
+//      _3 = const {transmute(0x01): std::option::Option<bool>};
 //      _4 = const 1isize;
 //      switchInt(const 1isize) -> [1isize: bb2, otherwise: bb1];
 //  }