--- a/frankenphp.c
+++ b/frankenphp.c
@@ -1254,6 +1254,12 @@

   go_frankenphp_shutdown_main_thread();

+  /* spc-pgo: explicit profile flush so the cgo-instrumented frankenphp
+   * still writes .profraw on Go-runtime exit (which bypasses libc atexit).
+   * Weak symbol → no-op in non-PGO builds. */
+  { extern int __llvm_profile_write_file(void) __attribute__((weak));
+    if (__llvm_profile_write_file) __llvm_profile_write_file(); }
+
   return NULL;
 }