diff --git a/Cargo.lock b/Cargo.lock
index 9bffb936bd..95af9bb638 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -25,6 +25,7 @@ checksum = "b4668fb0ea861c1df094127ac5f1da3409a82116a4ba74fca2e58ef927159bb3"
 [[package]]
 name = "redox_syscall"
 version = "0.3.5"
+source = "git+https://gitlab.redox-os.org/4lDO2/syscall.git?branch=better_fmap#f0976e1d6020e6854ca30ed1f6d61b10dfc4fa58"
 dependencies = [
  "bitflags",
 ]
diff --git a/Cargo.toml b/Cargo.toml
index 846a17fd2b..05de5520a5 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -4,4 +4,4 @@ name = "ipcd"
 version = "0.1.0"
 [dependencies]
 libc = "0.2"
-redox_syscall = { path = "../../kernel/source/syscall" }
+redox_syscall = { git = "https://gitlab.redox-os.org/4lDO2/syscall.git", branch = "better_fmap" }
diff --git a/src/main.rs b/src/main.rs
index 0c45d7d102..bde573ea2a 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -1,3 +1,5 @@
+#![feature(int_roundings)]
+
 use std::{
     collections::VecDeque,
     fs::File,
@@ -113,7 +115,7 @@ fn main() -> Result<(), Box<dyn std::error::Error>> {
                             Ok(0) => break true,
                             Ok(_) => {
                                 unsafe {
-                                    shm.do_handle(&mut packet);
+                                    shm.handle(&mut packet);
                                 }
                                 shm.socket.write(&packet)?;
                             },
diff --git a/src/shm.rs b/src/shm.rs
index f1855e1ee9..db7c8a1ce7 100644
--- a/src/shm.rs
+++ b/src/shm.rs
@@ -33,41 +33,6 @@ impl ShmScheme {
                 .open(":shm")?
         })
     }
-    pub unsafe fn do_handle(&mut self, packet: &mut Packet) {
-        match packet.a {
-            KSMSG_MMAP_PREP | KSMSG_MMAP => {
-                let req_file = packet.b;
-                let req_flags = MapFlags::from_bits_truncate(packet.c);
-                let req_page_count = packet.d;
-                let req_offset = u64::from(packet.uid) | (u64::from(packet.gid) << 32);
-
-                let res = self.ksmsg_mmap(req_file, req_flags, req_offset, req_page_count);
-
-                *packet = Packet {
-                    id: packet.id,
-                    a: syscall::Error::mux(res),
-                    ..Packet::default()
-                };
-            }
-            _ => self.handle(packet),
-        }
-    }
-    pub fn ksmsg_mmap(&mut self, id: usize, _flags: MapFlags, offset: u64, page_count: usize) -> Result<usize> {
-        let path = self.handles.get(&id).ok_or(Error::new(EBADF))?;
-        let total_size = offset as usize + page_count * PAGE_SIZE;
-        match self.maps.get_mut(path).expect("handle pointing to nothing").buffer {
-            Some(ref mut buf) => {
-                if total_size > buf.len() {
-                    return Err(Error::new(ERANGE));
-                }
-                Ok(buf.as_ptr() + offset as usize)
-            },
-            ref mut buf @ None => {
-                *buf = Some(MmapGuard::alloc(page_count)?);
-                Ok(buf.as_mut().unwrap().as_ptr() + offset as usize)
-            }
-        }
-    }
 }
 
 impl SchemeMut for ShmScheme {
@@ -110,6 +75,22 @@ impl SchemeMut for ShmScheme {
         }
         Ok(0)
     }
+    fn mmap_prep(&mut self, id: usize, offset: u64, size: usize, flags: MapFlags) -> Result<usize> {
+        let path = self.handles.get(&id).ok_or(Error::new(EBADF))?;
+        let total_size = offset as usize + size;
+        match self.maps.get_mut(path).expect("handle pointing to nothing").buffer {
+            Some(ref mut buf) => {
+                if total_size > buf.len() {
+                    return Err(Error::new(ERANGE));
+                }
+                Ok(buf.as_ptr() + offset as usize)
+            },
+            ref mut buf @ None => {
+                *buf = Some(MmapGuard::alloc(size.div_ceil(PAGE_SIZE))?);
+                Ok(buf.as_mut().unwrap().as_ptr() + offset as usize)
+            }
+        }
+    }
 }
 
 pub struct MmapGuard {