diff --git a/include/picrin.h b/include/picrin.h
index 3c5c0c84..0af29e40 100644
--- a/include/picrin.h
+++ b/include/picrin.h
@@ -66,7 +66,9 @@ pic_value pic_eval(pic_state *, pic_value, struct pic_env *);
 pic_value pic_run(pic_state *, struct pic_proc *, pic_value);
 struct pic_proc *pic_codegen(pic_state *, pic_value, struct pic_env *);
 
-void pic_raise(pic_state *, const char *);
+void pic_abort(pic_state *, const char *);
+void pic_raise(pic_state *, pic_value);
+void pic_error(pic_state *, const char *, ...);
 
 void pic_debug(pic_state *, pic_value);
 
diff --git a/src/codegen.c b/src/codegen.c
index 38993077..5ec0c652 100644
--- a/src/codegen.c
+++ b/src/codegen.c
@@ -204,7 +204,7 @@ pic_gen(pic_state *pic, struct pic_irep *irep, pic_value obj, struct pic_env *en
 
     b = env_lookup(pic, obj, env, &depth, &idx);
     if (! b) {
-      pic_raise(pic, "unbound variable");
+      pic_abort(pic, "unbound variable");
     }
 
     if (depth == -1) {		/* global */
@@ -218,7 +218,7 @@ pic_gen(pic_state *pic, struct pic_irep *irep, pic_value obj, struct pic_env *en
       irep->clen++;
     }
     else {			/* nonlocal */
-      pic_raise(pic, "reference to closed variable not supported");
+      pic_abort(pic, "reference to closed variable not supported");
     }
     break;
   }
@@ -362,7 +362,7 @@ pic_gen(pic_state *pic, struct pic_irep *irep, pic_value obj, struct pic_env *en
   case PIC_TT_PROC:
   case PIC_TT_UNDEF:
   case PIC_TT_PORT: {
-    pic_raise(pic, "invalid expression given");
+    pic_abort(pic, "invalid expression given");
   }
   }
 }
diff --git a/src/error.c b/src/error.c
index 9efcea1d..5ac13860 100644
--- a/src/error.c
+++ b/src/error.c
@@ -4,8 +4,8 @@
 #include "picrin.h"
 
 void
-pic_raise(pic_state *pic, const char *str)
+pic_abort(pic_state *pic, const char *msg)
 {
-  puts(str);
+  puts(msg);
   abort();
 }
diff --git a/src/gc.c b/src/gc.c
index dc9fa2da..4884c3b3 100644
--- a/src/gc.c
+++ b/src/gc.c
@@ -40,7 +40,7 @@ pic_alloc(pic_state *pic, size_t size)
 
   ptr = malloc(size);
   if (ptr == NULL) {
-    pic_raise(pic, "memory exhausted");
+    pic_abort(pic, "memory exhausted");
   }
   return ptr;
 }
@@ -50,7 +50,7 @@ pic_realloc(pic_state *pic, void *ptr, size_t size)
 {
   ptr = realloc(ptr, size);
   if (ptr == NULL) {
-    pic_raise(pic, "memory exhausted");
+    pic_abort(pic, "memory exhausted");
   }
   return ptr;
 }
@@ -65,7 +65,7 @@ static void
 gc_protect(pic_state *pic, struct pic_object *obj)
 {
   if (pic->arena_idx >= PIC_ARENA_SIZE) {
-    pic_raise(pic, "arena overflow");
+    pic_abort(pic, "arena overflow");
   }
   pic->arena[pic->arena_idx++] = obj;
 }
@@ -149,7 +149,7 @@ gc_mark_object(pic_state *pic, struct pic_object *obj)
     break;
   }
   default:
-    pic_raise(pic, "logic flaw");
+    pic_abort(pic, "logic flaw");
   }
 }
 
@@ -243,7 +243,7 @@ gc_finalize_object(pic_state *pic, struct pic_object *obj)
     break;
   }
   default:
-    pic_raise(pic, "logic flaw");
+    pic_abort(pic, "logic flaw");
   }
 }
 
@@ -349,7 +349,7 @@ pic_obj_alloc(pic_state *pic, size_t size, enum pic_tt tt)
     pic_gc_run(pic);
     obj = (struct pic_object *)gc_alloc(pic, size);
     if (obj == NULL)
-      pic_raise(pic, "GC memory exhausted");
+      pic_abort(pic, "GC memory exhausted");
   }
   obj->tt = tt;