diff --git a/Makefile b/Makefile
index b90f836af..d4dd066ca 100644
--- a/Makefile
+++ b/Makefile
@@ -16,7 +16,10 @@ export MOROS_KEYBOARD = $(keyboard)
 # Build userspace binaries
 user-nasm:
 	basename -s .s dsk/src/bin/*.s | xargs -I {} \
-		nasm dsk/src/bin/{}.s -o dsk/bin/{}
+    nasm dsk/src/bin/{}.s -o dsk/bin/{}.tmp
+	basename -s .s dsk/src/bin/*.s | xargs -I {} \
+		sh -c "printf '\x7FBIN' | cat - dsk/bin/{}.tmp > dsk/bin/{}"
+	rm dsk/bin/*.tmp
 user-rust:
 	basename -s .rs src/bin/*.rs | xargs -I {} \
 		touch dsk/bin/{}
diff --git a/src/api/process.rs b/src/api/process.rs
index 7a168e3d7..641f3f538 100644
--- a/src/api/process.rs
+++ b/src/api/process.rs
@@ -2,8 +2,7 @@ use crate::api::syscall;
 
 pub fn spawn(path: &str) -> Result<(), ()> {
     if syscall::info(path).is_some() {
-        syscall::spawn(path);
-        return Ok(());
+        return syscall::spawn(path);
     }
     Err(())
 }
diff --git a/src/api/syscall.rs b/src/api/syscall.rs
index 89a08df87..708341bb7 100644
--- a/src/api/syscall.rs
+++ b/src/api/syscall.rs
@@ -80,10 +80,15 @@ pub fn close(handle: usize) {
     unsafe { syscall!(CLOSE, handle as usize) };
 }
 
-pub fn spawn(path: &str) {
+pub fn spawn(path: &str) -> Result<(), ()> {
     let ptr = path.as_ptr() as usize;
     let len = path.len() as usize;
-    unsafe { syscall!(SPAWN, ptr, len) };
+    let res = unsafe { syscall!(SPAWN, ptr, len) } as isize;
+    if res.is_negative() {
+        Err(())
+    } else {
+        Ok(())
+    }
 }
 
 pub fn reboot() {
diff --git a/src/sys/allocator.rs b/src/sys/allocator.rs
index 4043100f4..ce474e5f1 100644
--- a/src/sys/allocator.rs
+++ b/src/sys/allocator.rs
@@ -1,4 +1,5 @@
 use crate::sys;
+
 use alloc::slice::SliceIndex;
 use alloc::sync::Arc;
 use alloc::vec;
diff --git a/src/sys/fs/dir_entry.rs b/src/sys/fs/dir_entry.rs
index a146ce180..cac941b48 100644
--- a/src/sys/fs/dir_entry.rs
+++ b/src/sys/fs/dir_entry.rs
@@ -117,6 +117,10 @@ impl FileInfo {
         self.name.clone()
     }
 
+    pub fn kind(&self) -> FileType {
+        self.kind
+    }
+
     // TODO: Duplicated from dir entry
     pub fn is_dir(&self) -> bool {
         self.kind == FileType::Dir
diff --git a/src/sys/process.rs b/src/sys/process.rs
index 0a50fd6b4..6746045e5 100644
--- a/src/sys/process.rs
+++ b/src/sys/process.rs
@@ -209,7 +209,8 @@ pub struct Registers {
     pub rax: usize,
 }
 
-const ELF_MAGIC: [u8; 4] = [0x74, b'E', b'L', b'F'];
+const ELF_MAGIC: [u8; 4] = [0x7F, b'E', b'L', b'F'];
+const BIN_MAGIC: [u8; 4] = [0x7F, b'B', b'I', b'N'];
 
 #[derive(Clone, Debug)]
 pub struct Process {
@@ -242,13 +243,16 @@ impl Process {
         }
     }
 
-    pub fn spawn(bin: &[u8]) {
+    pub fn spawn(bin: &[u8]) -> Result<(), ()> {
         if let Ok(pid) = Self::create(bin) {
             let proc = {
                 let table = PROCESS_TABLE.read();
                 table[pid].clone()
             };
             proc.exec();
+            Ok(())
+        } else {
+            Err(())
         }
     }
 
@@ -256,12 +260,12 @@ impl Process {
         // Allocate some memory for the code and the stack of the program
         let code_size = 1 * PAGE_SIZE;
         let code_addr = CODE_ADDR.fetch_add(code_size, Ordering::SeqCst);
-        sys::allocator::alloc_pages(code_addr, code_size);
 
         let mut entry_point = 0;
         let code_ptr = code_addr as *mut u8;
         if bin[0..4] == ELF_MAGIC { // ELF binary
             if let Ok(obj) = object::File::parse(bin) {
+                sys::allocator::alloc_pages(code_addr, code_size);
                 entry_point = obj.entry();
                 for segment in obj.segments() {
                     let addr = segment.address() as usize;
@@ -275,13 +279,16 @@ impl Process {
                     }
                 }
             }
-        } else { // Raw binary
-            for (i, op) in bin.iter().enumerate() {
+        } else if bin[0..4] == BIN_MAGIC { // Flat binary
+            sys::allocator::alloc_pages(code_addr, code_size);
+            for (i, op) in bin.iter().skip(4).enumerate() {
                 unsafe {
                     let ptr = code_ptr.add(i);
                     core::ptr::write(ptr, *op);
                 }
             }
+        } else {
+            return Err(());
         }
 
         let mut table = PROCESS_TABLE.write();
diff --git a/src/sys/syscall/mod.rs b/src/sys/syscall/mod.rs
index 754813d49..3dc6a6b28 100644
--- a/src/sys/syscall/mod.rs
+++ b/src/sys/syscall/mod.rs
@@ -67,8 +67,7 @@ pub fn dispatcher(n: usize, arg1: usize, arg2: usize, arg3: usize) -> usize {
             let ptr = sys::process::ptr_from_addr(arg1 as u64);
             let len = arg2;
             let path = unsafe { core::str::from_utf8_unchecked(core::slice::from_raw_parts(ptr, len)) };
-            service::spawn(path);
-            0
+            service::spawn(path) as usize
         }
         number::STOP => {
             service::stop(arg1)
diff --git a/src/sys/syscall/service.rs b/src/sys/syscall/service.rs
index ba97bb80a..ecbfb52e1 100644
--- a/src/sys/syscall/service.rs
+++ b/src/sys/syscall/service.rs
@@ -89,8 +89,9 @@ pub fn spawn(path: &str) -> isize {
         let mut buf = vec![0; file.size()];
         if let Ok(bytes) = file.read(&mut buf) {
             buf.resize(bytes, 0);
-            Process::spawn(&buf);
-            return 0;
+            if Process::spawn(&buf).is_ok() {
+                return 0;
+            }
         }
     }
     -1
diff --git a/src/usr/shell.rs b/src/usr/shell.rs
index 5e6f2ee12..fa3fbf3f0 100644
--- a/src/usr/shell.rs
+++ b/src/usr/shell.rs
@@ -1,8 +1,10 @@
 use crate::{api, sys, usr};
+use crate::api::console::Style;
 use crate::api::fs;
-use crate::api::regex::Regex;
 use crate::api::prompt::Prompt;
-use crate::api::console::Style;
+use crate::api::regex::Regex;
+use crate::api::syscall;
+use crate::sys::fs::FileType;
 
 use alloc::collections::btree_map::BTreeMap;
 use alloc::format;
@@ -304,11 +306,28 @@ pub fn exec(cmd: &str, env: &mut BTreeMap<String, String>) -> ExitCode {
         "2048"                 => usr::pow::main(&args),
         "time"                 => usr::time::main(&args),
         "proc"                 => proc(&args),
-        cmd                    => {
-            if api::process::spawn(cmd).is_ok() {
-                ExitCode::CommandSuccessful
-            } else {
-                ExitCode::CommandUnknown
+        _                      => {
+            let mut path = fs::realpath(args[0]);
+            if path.len() > 1 {
+                path = path.trim_end_matches('/').into();
+            }
+            match syscall::info(&path).map(|info| info.kind()) {
+                Some(FileType::Dir) => {
+                    sys::process::set_dir(&path);
+                    ExitCode::CommandSuccessful
+                }
+                Some(FileType::File) => {
+                    if api::process::spawn(&path).is_ok() {
+                        ExitCode::CommandSuccessful
+                    } else {
+                        error!("'{}' is not executable", path);
+                        ExitCode::CommandError
+                    }
+                }
+                _ => {
+                    error!("Could not execute '{}'", cmd);
+                    ExitCode::CommandUnknown
+                }
             }
         }
     };