diff --git a/src/rustup-utils/src/lib.rs b/src/rustup-utils/src/lib.rs
index 33a3b1b06a..987caaab19 100644
--- a/src/rustup-utils/src/lib.rs
+++ b/src/rustup-utils/src/lib.rs
@@ -1,6 +1,5 @@
 #![feature(core_intrinsics)] // For type_name().
 #![feature(fundamental)]
-#![feature(step_by)]
 #![recursion_limit = "1024"] // for error_chain!
 
 extern crate hyper;
diff --git a/src/rustup-utils/src/sha2.rs b/src/rustup-utils/src/sha2.rs
index 1b1b6877ac..b812407dcd 100644
--- a/src/rustup-utils/src/sha2.rs
+++ b/src/rustup-utils/src/sha2.rs
@@ -361,7 +361,8 @@ impl Engine256State {
 
         // Putting the message schedule inside the same loop as the round calculations allows for
         // the compiler to generate better code.
-        for t in (0..48).step_by(8) {
+        let mut t = 0;
+        while t < 48 {
             schedule_round!(t + 16);
             schedule_round!(t + 17);
             schedule_round!(t + 18);
@@ -379,9 +380,12 @@ impl Engine256State {
             sha2_round!(d, e, f, g, h, a, b, c, K32, t + 5);
             sha2_round!(c, d, e, f, g, h, a, b, K32, t + 6);
             sha2_round!(b, c, d, e, f, g, h, a, K32, t + 7);
+
+            t += 8;
         }
 
-        for t in (48..64).step_by(8) {
+        let mut t = 48;
+        while t < 64 {
             sha2_round!(a, b, c, d, e, f, g, h, K32, t);
             sha2_round!(h, a, b, c, d, e, f, g, K32, t + 1);
             sha2_round!(g, h, a, b, c, d, e, f, K32, t + 2);
@@ -390,6 +394,8 @@ impl Engine256State {
             sha2_round!(d, e, f, g, h, a, b, c, K32, t + 5);
             sha2_round!(c, d, e, f, g, h, a, b, K32, t + 6);
             sha2_round!(b, c, d, e, f, g, h, a, K32, t + 7);
+
+            t += 8;
         }
 
         self.h0 = self.h0.wrapping_add(a);