diff --git a/src/sys_quotactl.rs b/src/sys_quotactl.rs
index 8a243fd..b125502 100644
--- a/src/sys_quotactl.rs
+++ b/src/sys_quotactl.rs
@@ -113,7 +113,7 @@ pub async fn q_getinfo(
         let mut data: dqinfo = unsafe { mem::zeroed() };
         let special = special.as_ref().map(|c| c.as_ptr()).unwrap_or(ptr::null());
         sc_libc_try!(unsafe {
-            libc::quotactl(cmd, special, id, &mut data as *mut dqinfo as *mut i8)
+            libc::quotactl(cmd, special, id, &mut data as *mut dqinfo as *mut u8)
         });
 
         msg.mem_write_struct(addr, &data)?;
@@ -143,7 +143,7 @@ pub async fn q_setinfo(
                 cmd,
                 special.as_ptr(),
                 id,
-                &mut data as *mut dqinfo as *mut i8,
+                &mut data as *mut dqinfo as *mut u8,
             )
         });
 
@@ -166,7 +166,7 @@ pub async fn q_getfmt(
 
         let mut data: u32 = 0;
         let special = special.as_ref().map(|c| c.as_ptr()).unwrap_or(ptr::null());
-        sc_libc_try!(unsafe { libc::quotactl(cmd, special, id, &mut data as *mut u32 as *mut i8) });
+        sc_libc_try!(unsafe { libc::quotactl(cmd, special, id, &mut data as *mut u32 as *mut u8) });
 
         msg.mem_write_struct(addr, &data)?;
         Ok(SyscallStatus::Ok(0))
@@ -257,7 +257,7 @@ pub async fn q_getquota(
                 cmd,
                 special.as_ptr(),
                 id,
-                &mut data as *mut libc::dqblk as *mut i8,
+                &mut data as *mut libc::dqblk as *mut u8,
             )
         });
 
@@ -290,7 +290,7 @@ pub async fn q_setquota(
                 cmd,
                 special.as_ptr(),
                 id,
-                &mut data as *mut libc::dqblk as *mut i8,
+                &mut data as *mut libc::dqblk as *mut u8,
             )
         });
 
@@ -323,7 +323,7 @@ pub async fn q_getnextquota(
                 cmd,
                 special.as_ptr(),
                 id,
-                &mut data as *mut nextdqblk as *mut i8,
+                &mut data as *mut nextdqblk as *mut u8,
             )
         });