diff --git a/src/unix/bsd/freebsdlike/freebsd/mod.rs b/src/unix/bsd/freebsdlike/freebsd/mod.rs
index 926fd020df99..0e8521633a09 100644
--- a/src/unix/bsd/freebsdlike/freebsd/mod.rs
+++ b/src/unix/bsd/freebsdlike/freebsd/mod.rs
@@ -4377,19 +4377,19 @@ f! {
     }
 
     pub unsafe fn CPU_SET(cpu: usize, cpuset: &mut cpuset_t) -> () {
-        let bitset_bits = 8 * size_of::<c_long>();
+        let bitset_bits = 8 * size_of_val(&cpuset.__bits[0]);
         let (idx, offset) = (cpu / bitset_bits, cpu % bitset_bits);
         cpuset.__bits[idx] |= 1 << offset;
     }
 
     pub unsafe fn CPU_CLR(cpu: usize, cpuset: &mut cpuset_t) -> () {
-        let bitset_bits = 8 * size_of::<c_long>();
+        let bitset_bits = 8 * size_of_val(&cpuset.__bits[0]);
         let (idx, offset) = (cpu / bitset_bits, cpu % bitset_bits);
         cpuset.__bits[idx] &= !(1 << offset);
     }
 
     pub unsafe fn CPU_ISSET(cpu: usize, cpuset: &cpuset_t) -> bool {
-        let bitset_bits = 8 * size_of::<c_long>();
+        let bitset_bits = 8 * size_of_val(&cpuset.__bits[0]);
         let (idx, offset) = (cpu / bitset_bits, cpu % bitset_bits);
         0 != cpuset.__bits[idx] & (1 << offset)
     }
@@ -4397,7 +4397,7 @@ f! {
     pub unsafe fn CPU_COUNT(cpuset: &cpuset_t) -> c_int {
         let mut s: u32 = 0;
         let cpuset_size = size_of::<cpuset_t>();
-        let bitset_size = size_of::<c_long>();
+        let bitset_size = size_of_val(&cpuset.__bits[0]);
         for i in &cpuset.__bits[..(cpuset_size / bitset_size)] {
             s += i.count_ones();
         }
diff --git a/src/unix/hurd/mod.rs b/src/unix/hurd/mod.rs
index 41547488a86c..9da69b287167 100644
--- a/src/unix/hurd/mod.rs
+++ b/src/unix/hurd/mod.rs
@@ -2579,7 +2579,7 @@ pub const SCHED_FIFO: c_int = 1;
 pub const SCHED_RR: c_int = 2;
 pub const _BITS_TYPES_STRUCT_SCHED_PARAM: usize = 1;
 pub const __CPU_SETSIZE: usize = 1024;
-pub const __NCPUBITS: usize = 8 * size_of::<__cpu_mask>();
+pub const __NCPUBITS: usize = __cpu_mask::BITS as usize;
 pub const CPU_SETSIZE: usize = 1024;
 
 // pthread.h