diff --git a/src/os.cpp b/src/os.cpp
index 75e6dd8658..0e3c3f9a60 100644
--- a/src/os.cpp
+++ b/src/os.cpp
@@ -994,23 +994,23 @@ int os_self_exe_path(Buf *out_path) {
     int ret1 = _NSGetExecutablePath(nullptr, &u32_len);
     assert(ret1 != 0);
 
-    // Allocate a buffer for this path.
-    Buf *path_tmp = buf_alloc_fixed(u32_len);
-    // Fill the buffer with the path, which may be a symlink.
-    int ret2 = _NSGetExecutablePath(buf_ptr(path_tmp), &u32_len);
+    // Make room for the executable path and resolved path in out_path,
+    // then subslice it for convenience.
+    buf_resize(out_path, u32_len + PATH_MAX);
+    Buf *tmp = buf_slice(out_path, 0, u32_len);
+    Buf *resolved = buf_slice(out_path, u32_len, u32_len + PATH_MAX);
+
+    // Fill the executable path.
+    int ret2 = _NSGetExecutablePath(buf_ptr(tmp), &u32_len);
     assert(ret2 == 0);
 
-    // Make a buffer with room for the real path.
-    Buf *resolve_tmp = buf_alloc_fixed(PATH_MAX);
+    // Resolve the real path from that.
+    char *real_path = realpath(buf_ptr(tmp), buf_ptr(resolved));
+    assert(real_path == buf_ptr(resolved));
 
-    // Fill it with the real resolved path.
-    char *real_path = realpath(buf_ptr(path_tmp), buf_ptr(resolve_tmp));
-    // IEEE Std 1003.1-2017: realpath() shall return a pointer to the
-    // buffer containing the resolved name.
-    assert(real_path == buf_ptr(resolve_tmp));
-
-    // Resize out_path and copy the resulting resolved absolute path.
-    buf_init_from_buf(out_path, resolve_tmp);
+    // Write the real path back into the beginning of out_path, resize.
+    buf_init_from_buf(out_path, resolved);
+    assert(buf_len(out_path) == buf_len(resolved));
     return 0;
 #elif defined(ZIG_OS_LINUX)
     buf_resize(out_path, 256);