diff --git a/gc.c b/gc.c
index ee8b7bc376..f47f82e26b 100644
--- a/gc.c
+++ b/gc.c
@@ -636,7 +636,7 @@ typedef struct gc_function_map {
     // Statistics
     VALUE (*set_measure_total_time)(void *objspace_ptr, VALUE flag);
     VALUE (*get_measure_total_time)(void *objspace_ptr);
-    VALUE (*get_profile_total_time)(void *objspace_ptr);
+    unsigned long long (*get_profile_total_time)(void *objspace_ptr);
     size_t (*gc_count)(void *objspace_ptr);
     VALUE (*latest_gc_info)(void *objspace_ptr, VALUE key);
     size_t (*stat)(void *objspace_ptr, VALUE hash_or_sym);
diff --git a/gc.rb b/gc.rb
index f714fba749..7b943f1d80 100644
--- a/gc.rb
+++ b/gc.rb
@@ -352,7 +352,7 @@ module GC
   # Return measured \GC total time in nano seconds.
   def self.total_time
     Primitive.cexpr! %{
-      rb_gc_impl_get_profile_total_time(rb_gc_get_objspace())
+      ULL2NUM(rb_gc_impl_get_profile_total_time(rb_gc_get_objspace()))
     }
   end
 end
diff --git a/gc/default.c b/gc/default.c
index d959e108ab..149eae5971 100644
--- a/gc/default.c
+++ b/gc/default.c
@@ -1522,7 +1522,7 @@ rb_gc_impl_set_event_hook(void *objspace_ptr, const rb_event_flag_t event)
     objspace->flags.has_newobj_hook = !!(objspace->hook_events & RUBY_INTERNAL_EVENT_NEWOBJ);
 }
 
-VALUE
+unsigned long long
 rb_gc_impl_get_profile_total_time(void *objspace_ptr)
 {
     rb_objspace_t *objspace = objspace_ptr;
@@ -1530,7 +1530,7 @@ rb_gc_impl_get_profile_total_time(void *objspace_ptr)
     unsigned long long marking_time = objspace->profile.marking_time_ns;
     unsigned long long sweeping_time = objspace->profile.sweeping_time_ns;
 
-    return ULL2NUM(marking_time + sweeping_time);
+    return marking_time + sweeping_time;
 }
 
 VALUE
diff --git a/gc/gc_impl.h b/gc/gc_impl.h
index 12527845f7..ec47c9fe7e 100644
--- a/gc/gc_impl.h
+++ b/gc/gc_impl.h
@@ -87,7 +87,7 @@ GC_IMPL_FN VALUE rb_gc_impl_object_id_to_ref(void *objspace_ptr, VALUE object_id
 // Statistics
 GC_IMPL_FN VALUE rb_gc_impl_set_measure_total_time(void *objspace_ptr, VALUE flag);
 GC_IMPL_FN VALUE rb_gc_impl_get_measure_total_time(void *objspace_ptr);
-GC_IMPL_FN VALUE rb_gc_impl_get_profile_total_time(void *objspace_ptr);
+GC_IMPL_FN unsigned long long rb_gc_impl_get_profile_total_time(void *objspace_ptr);
 GC_IMPL_FN size_t rb_gc_impl_gc_count(void *objspace_ptr);
 GC_IMPL_FN VALUE rb_gc_impl_latest_gc_info(void *objspace_ptr, VALUE key);
 GC_IMPL_FN size_t rb_gc_impl_stat(void *objspace_ptr, VALUE hash_or_sym);