diff --git a/src/lib/libast/features/vmalloc b/src/lib/libast/features/vmalloc
index 5de9fbfc4..284f503f0 100644
--- a/src/lib/libast/features/vmalloc
+++ b/src/lib/libast/features/vmalloc
@@ -191,7 +191,7 @@ tst	malloc_hook note{ gnu malloc hooks work }end execute{
 	        __realloc_hook = test_realloc_hook;
 	}
 
-	typeof (__malloc_initialize_hook) __malloc_initialize_hook = test_initialize_hook;
+	void    (*__malloc_initialize_hook)(void) = test_initialize_hook;
 
 	int main()
 	{
diff --git a/src/lib/libast/vmalloc/malloc.c b/src/lib/libast/vmalloc/malloc.c
index 90b0336ab..ae77a2212 100644
--- a/src/lib/libast/vmalloc/malloc.c
+++ b/src/lib/libast/vmalloc/malloc.c
@@ -823,7 +823,7 @@ static void vm_initialize_hook(void)
 	__realloc_hook = vm_realloc_hook;
 }
 
-typeof (__malloc_initialize_hook) __malloc_initialize_hook = vm_initialize_hook;
+void	(*__malloc_initialize_hook)(void) = vm_initialize_hook;
 
 #if 0 /* 2012-02-29 this may be needed to cover shared libs */