diff --git a/common/channel.cc b/common/channel.cc
index ef4ea19..787e9f4 100644
--- a/common/channel.cc
+++ b/common/channel.cc
@@ -401,7 +401,14 @@ Channel::PosixSharedMemoryName(const std::string &shadow_file) {
   // Use the inode number (unique per file) to make the shm file name.
   // st_ino is unsigned and can be 64-bit on some systems (e.g. QNX), so
   // promote to uint64_t before formatting.
-  return absl::StrFormat("subspace_%llu",
+  //
+  // The leading '/' is required: POSIX shm_open names that do not start with
+  // '/' are implementation-defined. On QNX they resolve relative to the
+  // process cwd, so a publisher started under
+  // /applications/install/opt/<App>/ creates objects that a subscriber
+  // started from '/' cannot open (ENOENT). A leading slash places the object
+  // in the global shm namespace (macOS also requires a leading '/').
+  return absl::StrFormat("/subspace_%llu",
                          static_cast<unsigned long long>(st.st_ino));
 }
 #endif
diff --git a/rust_client/src/publisher.rs b/rust_client/src/publisher.rs
index 0d96a7f..f69b1d3 100644
--- a/rust_client/src/publisher.rs
+++ b/rust_client/src/publisher.rs
@@ -880,7 +880,9 @@ fn create_shm(name: &str, size: usize) -> crate::error::Result<RawFd> {
 #[cfg(not(target_os = "linux"))]
 fn posix_shm_name(shadow_path: &str) -> crate::error::Result<String> {
     let stat = crate::syscall_shim::shim_stat(shadow_path)?;
-    Ok(format!("subspace_{}", stat.st_ino))
+    // POSIX shm names must use the global namespace so Rust and C++ clients
+    // resolve the same object even when their working directories differ.
+    Ok(format!("/subspace_{}", stat.st_ino))
 }
 
 #[cfg(not(target_os = "linux"))]