diff --git a/library/stdarch/src/runtime/aarch64.rs b/library/stdarch/src/runtime/aarch64.rs
index 5d10fc06e3ab..4c546d9380aa 100644
--- a/library/stdarch/src/runtime/aarch64.rs
+++ b/library/stdarch/src/runtime/aarch64.rs
@@ -32,11 +32,11 @@ pub enum __Feature {
 }
 
 pub fn detect_features<T: linux::FeatureQuery>(mut x: T) -> usize {
-    let value: usize = 0;
+    let mut value: usize = 0;
     {
         let mut enable_feature = |f| {
             if x.has_feature(&f) {
-                bit::set(value, f as u32);
+                value = bit::set(value, f as u32);
             }
         };
         enable_feature(__Feature::asimd);
diff --git a/library/stdarch/src/runtime/arm.rs b/library/stdarch/src/runtime/arm.rs
index 60ef909fca12..997eac7527f4 100644
--- a/library/stdarch/src/runtime/arm.rs
+++ b/library/stdarch/src/runtime/arm.rs
@@ -29,11 +29,11 @@ pub enum __Feature {
 }
 
 pub fn detect_features<T: linux::FeatureQuery>(mut x: T) -> usize {
-    let value: usize = 0;
+    let mut value: usize = 0;
     {
         let mut enable_feature = |f| {
             if x.has_feature(&f) {
-                bit::set(value, f as u32);
+                value = bit::set(value, f as u32);
             }
         };
         enable_feature(__Feature::neon);