diff --git a/src/c/threads/process.d b/src/c/threads/process.d
index bde09e30d..a3bb9894d 100755
--- a/src/c/threads/process.d
+++ b/src/c/threads/process.d
@@ -189,7 +189,7 @@ thread_cleanup(void *aux)
   cl_env_ptr env = process->process.env;
   /* The following flags will disable all interrupts. */
   AO_store_full((AO_t*)&process->process.phase, ECL_PROCESS_EXITING);
-  ecl_disable_interrupts_env(env);
+  if (env) ecl_disable_interrupts_env(env);
 #ifdef HAVE_SIGPROCMASK
   /* ...but we might get stray signals. */
   {