diff --git a/lib/cont.c b/lib/cont.c
index e8034577..ff5713ec 100644
--- a/lib/cont.c
+++ b/lib/cont.c
@@ -104,7 +104,7 @@ pic_alloca_cont(pic_state *pic)
 }
 
 static pic_value
-values(pic_state *pic, int argc, pic_value *argv)
+valuesk(pic_state *pic, int argc, pic_value *argv)
 {
   int i;
 
@@ -123,7 +123,7 @@ pic_callcc(pic_state *pic, pic_value proc)
   volatile struct cont *cont = pic_alloca_cont(pic);
 
   if (PIC_SETJMP(pic, jmp)) {
-    return values(pic, cont->retc, cont->retv);
+    return valuesk(pic, cont->retc, cont->retv);
   }
   else {
     pic_value val;
@@ -159,7 +159,7 @@ pic_vvalues(pic_state *pic, int n, va_list ap)
   for (i = 0; i < n; ++i) {
     retv[i] = va_arg(ap, pic_value);
   }
-  return values(pic, n, retv);
+  return valuesk(pic, n, retv);
 }
 
 int
@@ -196,7 +196,7 @@ pic_cont_values(pic_state *pic)
 
   pic_get_args(pic, "*", &argc, &argv);
 
-  return values(pic, argc, argv);
+  return valuesk(pic, argc, argv);
 }
 
 static pic_value
diff --git a/lib/include/picrin/setup.h b/lib/include/picrin/setup.h
index 22b916eb..298f58b5 100644
--- a/lib/include/picrin/setup.h
+++ b/lib/include/picrin/setup.h
@@ -173,7 +173,7 @@ typedef unsigned long uint32_t;
 # define GCC_VERSION (__GNUC__ * 10000 + __GNUC_MINOR__ * 100 + __GNUC_PATCHLEVEL__)
 #endif
 #if GCC_VERSION >= 40500 || __clang__
-# define PIC_UNREACHABLE() (__builtin_unreachable())
+# define PIC_UNREACHABLE() (assert(false), __builtin_unreachable())
 #else
 # define PIC_UNREACHABLE() (assert(false))
 #endif