diff --git a/lib/libc/stdbit/stdc_has_single_bit.c b/lib/libc/stdbit/stdc_has_single_bit.c
--- a/lib/libc/stdbit/stdc_has_single_bit.c
+++ b/lib/libc/stdbit/stdc_has_single_bit.c
@@ -10,29 +10,29 @@
 bool
 stdc_has_single_bit_uc(unsigned char x)
 {
-	return (x != 0 && (x & x - 1) == 0);
+	return (x != 0 && (x & (x - 1)) == 0);
 }
 
 bool
 stdc_has_single_bit_us(unsigned short x)
 {
-	return (x != 0 && (x & x - 1) == 0);
+	return (x != 0 && (x & (x - 1)) == 0);
 }
 
 bool
 stdc_has_single_bit_ui(unsigned int x)
 {
-	return (x != 0 && (x & x - 1) == 0);
+	return (x != 0 && (x & (x - 1)) == 0);
 }
 
 bool
 stdc_has_single_bit_ul(unsigned long x)
 {
-	return (x != 0 && (x & x - 1) == 0);
+	return (x != 0 && (x & (x - 1)) == 0);
 }
 
 bool
 stdc_has_single_bit_ull(unsigned long long x)
 {
-	return (x != 0 && (x & x - 1) == 0);
+	return (x != 0 && (x & (x - 1)) == 0);
 }