diff --git a/src/c/format.d b/src/c/format.d
index b9a525dc0..6c653e92e 100644
--- a/src/c/format.d
+++ b/src/c/format.d
@@ -98,14 +98,14 @@ get_aux_stream(void)
   cl_env_ptr env = ecl_process_env();
   cl_object stream;
 
-  ecl_disable_interrupts_env(env);
-  if (env->fmt_aux_stream == ECL_NIL) {
-    stream = ecl_make_string_output_stream(64, 1);
-  } else {
-    stream = env->fmt_aux_stream;
-    env->fmt_aux_stream = ECL_NIL;
-  }
-  ecl_enable_interrupts_env(env);
+  ECL_WITHOUT_INTERRUPTS_BEGIN(env) {
+    if (env->fmt_aux_stream == ECL_NIL) {
+      stream = ecl_make_string_output_stream(64, 1);
+    } else {
+      stream = env->fmt_aux_stream;
+      env->fmt_aux_stream = ECL_NIL;
+    }
+  } ECL_WITHOUT_INTERRUPTS_END;
   return stream;
 }
 
diff --git a/src/c/unixint.d b/src/c/unixint.d
index 127d2c87b..dd25da914 100644
--- a/src/c/unixint.d
+++ b/src/c/unixint.d
@@ -378,18 +378,31 @@ handle_all_queued_interrupt_safe(cl_env_ptr env)
         /* We have to save and later restore thread-local variables to
          * ensure that they don't get overwritten by the interrupting
          * code */
+        /* INV: - Frame, Binding and IHS stack manipulations are
+         *        interrupt safe
+         *      - The rest of the thread local variables are
+         *        guaranteed to be used in an interrupt safe way. This
+         *        is not true for the compiler environment and ffi
+         *        data, but it is unclear whether the DFFI or compiler
+         *        are thread safe anyway. */
         cl_object fun = env->function;
         cl_index nvalues = env->nvalues;
-        cl_object* values = ecl_alloc_atomic(ECL_MULTIPLE_VALUES_LIMIT*sizeof(cl_object));
+        cl_object values[ECL_MULTIPLE_VALUES_LIMIT];
         memcpy(values, env->values, ECL_MULTIPLE_VALUES_LIMIT*sizeof(cl_object));
         cl_object big_register[3];
         memcpy(big_register, env->big_register, 3*sizeof(cl_object));
+        cl_object packages_to_be_created = env->packages_to_be_created;
+        cl_object packages_to_be_created_p = env->packages_to_be_created_p;
         /* We might have been interrupted while we push/pop in the
          * stack. Increasing env->stack_top ensures that we don't
          * overwrite the topmost stack value. */
         env->stack_top++;
+        /* Finally we can handle the queued signals */
         handle_all_queued(env);
+        /* And restore thread local variables again */
         env->stack_top--;
+        env->packages_to_be_created_p = packages_to_be_created_p;
+        env->packages_to_be_created = packages_to_be_created;
         memcpy(env->big_register, big_register, 3*sizeof(cl_object));
         memcpy(env->values, values, ECL_MULTIPLE_VALUES_LIMIT*sizeof(cl_object));
         env->nvalues = nvalues;
diff --git a/src/h/external.h b/src/h/external.h
index 107e08a39..c1e8844bb 100755
--- a/src/h/external.h
+++ b/src/h/external.h
@@ -87,14 +87,16 @@ struct cl_env_struct {
         char *cs_barrier;
 
         /* Private variables used by different parts of ECL: */
-        /* ... the reader ... */
+        /* ... the reader and printer ... */
         cl_object string_pool;
 
         /* ... the compiler ... */
         struct cl_compiler_env *c_env;
 
         /* ... the formatter ... */
+#if !defined(ECL_CMU_FORMAT)
         cl_object fmt_aux_stream;
+#endif
 
         /* ... arithmetics ... */
         /* Note: if you change the size of these registers, change also