3 files changed, 8 insertions, 1 deletions
diff --git a/cont.c b/cont.c
index bdd775a8cb..59e97474fc 100644
--- a/cont.c
+++ b/cont.c
@@ -1865,6 +1865,9 @@ void
 rb_threadptr_root_fiber_setup(rb_thread_t *th)
 {
     rb_fiber_t *fiber = ruby_mimmalloc(sizeof(rb_fiber_t));
+    if (!fiber) {
+        rb_bug("%s", strerror(errno)); /* ... is it possible to call rb_bug here? */
+    }
     MEMZERO(fiber, rb_fiber_t, 1);
     fiber->cont.type = FIBER_CONTEXT;
     fiber->cont.saved_ec.fiber_ptr = fiber;
diff --git a/gc.c b/gc.c
index 97133e6a23..7365b6d6ec 100644
--- a/gc.c
+++ b/gc.c
@@ -10301,6 +10301,10 @@ ruby_mimmalloc(size_t size)
 #endif
     mem = malloc(size);
 #if CALC_EXACT_MALLOC_SIZE
+    if (!mem) {
+        return NULL;
+    }
+    else
     /* set 0 for consistency of allocated_size/allocations */
     {
         struct malloc_obj_info *info = mem;
diff --git a/internal.h b/internal.h
index 5b9b9b62bc..c10bac5358 100644
--- a/internal.h
+++ b/internal.h
@@ -1606,7 +1606,7 @@ NORETURN(void rb_syserr_fail_path_in(const char *func_name, int err, VALUE path)
 extern VALUE *ruby_initial_gc_stress_ptr;
 extern int ruby_disable_gc;
 void Init_heap(void);
-void *ruby_mimmalloc(size_t size);
+void *ruby_mimmalloc(size_t size) RUBY_ATTR_MALLOC;
 void ruby_mimfree(void *ptr);
 void rb_objspace_set_event_hook(const rb_event_flag_t event);
 #if USE_RGENGC