diff --git a/src/tracer/client.rs b/src/tracer/client.rs
index 311a163..b0f5474 100644
--- a/src/tracer/client.rs
+++ b/src/tracer/client.rs
@@ -674,8 +674,8 @@ impl TracerClient {
             e => e?,
         };
         let syscallno = syscall_no_from_regs!(regs);
+        log::trace!("Got syscall {} from {}", syscallno, pid);
         p.syscall = syscallno;
-        // log::trace!("pre syscall: {syscallno}");
         match syscallno {
             nix::libc::SYS_execveat => {
                 // int execveat(int dirfd, const char *pathname,
@@ -858,7 +858,7 @@ impl TracerClient {
     }
 
     fn instrument_exec(&mut self, pid: Pid, filename: &str, regs: &user_regs_struct, prog_idx: usize) -> anyhow::Result<()> {
-        if let Some(new_args) = if filename.ends_with("/docker") {
+        if let Some(new_args) = if filename.ends_with("/docker") && std::fs::metadata(&filename).is_ok() {
             let mut args = read_cstring_array(pid, syscall_arg(&regs, prog_idx + 1) as AddressType)?;
             if args.get(1).is_some_and(|c| c.to_str() == Ok("run")) {
                 let new_machine = self.allocate_machine()?;
diff --git a/src/tracer/docker.rs b/src/tracer/docker.rs
index 6e56b8f..fc93fd1 100644
--- a/src/tracer/docker.rs
+++ b/src/tracer/docker.rs
@@ -16,6 +16,7 @@ pub fn instrument_docker_run_execve(
     }
     #[derive(Default)]
     struct ArgsParsed<'a> {
+        preamble: Vec<&'a str>,
         args: Vec<Argument<'a>>,
         image: Option<&'a str>,
         cmd: Vec<&'a str>,
@@ -49,7 +50,7 @@ pub fn instrument_docker_run_execve(
         }
 
         fn reserialize(self) -> Vec<CString> {
-            let mut result = vec![];
+            let mut result = self.preamble.into_iter().map(|x| CString::new(x).unwrap()).collect::<Vec<_>>();
             for arg in self.args {
                 match arg {
                     Argument::Zero(a) => result.push(CString::new(a).unwrap()),
@@ -91,8 +92,8 @@ pub fn instrument_docker_run_execve(
     ]);
     let mut string_args = ArgsParsed::default();
     let mut args_iter = args.iter();
-    assert_eq!(args_iter.next().map(|x| x.to_str().unwrap()), Some("docker"));
-    assert_eq!(args_iter.next().map(|x| x.to_str().unwrap()), Some("run"));
+    string_args.preamble.push(args_iter.next().unwrap().to_str().unwrap());
+    string_args.preamble.push(args_iter.next().unwrap().to_str().unwrap());
     while let Some(arg) = args_iter.next() {
         let arg = arg.to_str()?;