diff --git a/include/picrin.h b/include/picrin.h
index f752d2cf..8dcd87b5 100644
--- a/include/picrin.h
+++ b/include/picrin.h
@@ -21,8 +21,8 @@
  * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  */
 
-#ifndef PICRIN_H__
-#define PICRIN_H__
+#ifndef PICRIN_H
+#define PICRIN_H
 
 #if defined(__cplusplus)
 extern "C" {
@@ -188,8 +188,8 @@ struct pic_lib *pic_open_library(pic_state *, pic_value);
 struct pic_lib *pic_find_library(pic_state *, pic_value);
 
 #define pic_deflibrary(pic, spec)                                       \
-  pic_deflibrary_helper__(pic, GENSYM(i), GENSYM(prev_lib), spec)
-#define pic_deflibrary_helper__(pic, i, prev_lib, spec)                 \
+  pic_deflibrary_helper_(pic, GENSYM(i), GENSYM(prev_lib), spec)
+#define pic_deflibrary_helper_(pic, i, prev_lib, spec)                  \
   for (int i = 0; ! i; )                                                \
     for (struct pic_lib *prev_lib; ! i; )                               \
       for ((prev_lib = pic->lib), pic_open_library(pic, pic_read_cstr(pic, spec)), pic_in_library(pic, pic_read_cstr(pic, spec)); ! i++; pic->lib = prev_lib)
diff --git a/include/picrin/blob.h b/include/picrin/blob.h
index 5837c04f..29a285e9 100644
--- a/include/picrin/blob.h
+++ b/include/picrin/blob.h
@@ -2,8 +2,8 @@
  * See Copyright Notice in picrin.h
  */
 
-#ifndef PICRIN_BLOB_H__
-#define PICRIN_BLOB_H__
+#ifndef PICRIN_BLOB_H
+#define PICRIN_BLOB_H
 
 #if defined(__cplusplus)
 extern "C" {
diff --git a/include/picrin/cont.h b/include/picrin/cont.h
index 0a0da9f1..eeabb798 100644
--- a/include/picrin/cont.h
+++ b/include/picrin/cont.h
@@ -2,8 +2,8 @@
  * See Copyright Notice in picrin.h
  */
 
-#ifndef PICRIN_CONT_H__
-#define PICRIN_CONT_H__
+#ifndef PICRIN_CONT_H
+#define PICRIN_CONT_H
 
 #if defined(__cplusplus)
 extern "C" {
diff --git a/include/picrin/data.h b/include/picrin/data.h
index a80ff209..0e59095d 100644
--- a/include/picrin/data.h
+++ b/include/picrin/data.h
@@ -2,8 +2,8 @@
  * See Copyright Notice in picrin.h
  */
 
-#ifndef PICRIN_DATA_H__
-#define PICRIN_DATA_H__
+#ifndef PICRIN_DATA_H
+#define PICRIN_DATA_H
 
 #if defined(__cplusplus)
 extern "C" {
diff --git a/include/picrin/dict.h b/include/picrin/dict.h
index bf681cad..8d6077af 100644
--- a/include/picrin/dict.h
+++ b/include/picrin/dict.h
@@ -2,8 +2,8 @@
  * See Copyright Notice in picrin.h
  */
 
-#ifndef PICRIN_DICT_H__
-#define PICRIN_DICT_H__
+#ifndef PICRIN_DICT_H
+#define PICRIN_DICT_H
 
 #if defined(__cplusplus)
 extern "C" {
diff --git a/include/picrin/error.h b/include/picrin/error.h
index bea590e2..5005346a 100644
--- a/include/picrin/error.h
+++ b/include/picrin/error.h
@@ -2,8 +2,8 @@
  * See Copyright Notice in picrin.h
  */
 
-#ifndef PICRIN_ERROR_H__
-#define PICRIN_ERROR_H__
+#ifndef PICRIN_ERROR_H
+#define PICRIN_ERROR_H
 
 #if defined(__cplusplus)
 extern "C" {
diff --git a/include/picrin/gc.h b/include/picrin/gc.h
index c5f33e6a..9f165d80 100644
--- a/include/picrin/gc.h
+++ b/include/picrin/gc.h
@@ -2,8 +2,8 @@
  * See Copyright Notice in picrin.h
  */
 
-#ifndef PICRIN_GC_H__
-#define PICRIN_GC_H__
+#ifndef PICRIN_GC_H
+#define PICRIN_GC_H
 
 #if defined(__cplusplus)
 extern "C" {
diff --git a/include/picrin/irep.h b/include/picrin/irep.h
index 4cb1cfba..c6e5befb 100644
--- a/include/picrin/irep.h
+++ b/include/picrin/irep.h
@@ -2,8 +2,8 @@
  * See Copyright Notice in picrin.h
  */
 
-#ifndef PICRIN_IREP_H__
-#define PICRIN_IREP_H__
+#ifndef PICRIN_IREP_H
+#define PICRIN_IREP_H
 
 #if defined(__cplusplus)
 extern "C" {
diff --git a/include/picrin/lib.h b/include/picrin/lib.h
index ba43e49d..98ab3ae8 100644
--- a/include/picrin/lib.h
+++ b/include/picrin/lib.h
@@ -2,8 +2,8 @@
  * See Copyright Notice in picrin.h
  */
 
-#ifndef PICRIN_LIB_H__
-#define PICRIN_LIB_H__
+#ifndef PICRIN_LIB_H
+#define PICRIN_LIB_H
 
 #if defined(__cplusplus)
 extern "C" {
diff --git a/include/picrin/macro.h b/include/picrin/macro.h
index e4f03b42..79148e51 100644
--- a/include/picrin/macro.h
+++ b/include/picrin/macro.h
@@ -2,8 +2,8 @@
  * See Copyright Notice in picrin.h
  */
 
-#ifndef PICRIN_MACRO_H__
-#define PICRIN_MACRO_H__
+#ifndef PICRIN_MACRO_H
+#define PICRIN_MACRO_H
 
 #if defined(__cplusplus)
 extern "C" {
diff --git a/include/picrin/pair.h b/include/picrin/pair.h
index 49de01cc..89cfe938 100644
--- a/include/picrin/pair.h
+++ b/include/picrin/pair.h
@@ -2,8 +2,8 @@
  * See Copyright Notice in picrin.h
  */
 
-#ifndef PICRIN_PAIR_H__
-#define PICRIN_PAIR_H__
+#ifndef PICRIN_PAIR_H
+#define PICRIN_PAIR_H
 
 #if defined(__cplusplus)
 extern "C" {
@@ -36,8 +36,8 @@ pic_value pic_list_by_array(pic_state *, size_t, pic_value *);
 pic_value pic_make_list(pic_state *, int, pic_value);
 
 #define pic_for_each(var, list)                                 \
-  pic_for_each_helper__(var, GENSYM(tmp), list)
-#define pic_for_each_helper__(var, tmp, list)                           \
+  pic_for_each_helper_(var, GENSYM(tmp), list)
+#define pic_for_each_helper_(var, tmp, list)                           \
   for (pic_value tmp = (list);                                          \
        pic_nil_p(tmp) ? false : ((var = pic_car(pic, tmp)), true);      \
        tmp = pic_cdr(pic, tmp))
diff --git a/include/picrin/port.h b/include/picrin/port.h
index e51d8759..334746cb 100644
--- a/include/picrin/port.h
+++ b/include/picrin/port.h
@@ -2,8 +2,8 @@
  * See Copyright Notice in picrin.h
  */
 
-#ifndef PICRIN_PORT_H__
-#define PICRIN_PORT_H__
+#ifndef PICRIN_PORT_H
+#define PICRIN_PORT_H
 
 #if defined(__cplusplus)
 extern "C" {
diff --git a/include/picrin/proc.h b/include/picrin/proc.h
index b443d3d9..bf5dda36 100644
--- a/include/picrin/proc.h
+++ b/include/picrin/proc.h
@@ -2,8 +2,8 @@
  * See Copyright Notice in picrin.h
  */
 
-#ifndef PICRIN_PROC_H__
-#define PICRIN_PROC_H__
+#ifndef PICRIN_PROC_H
+#define PICRIN_PROC_H
 
 #if defined(__cplusplus)
 extern "C" {
diff --git a/include/picrin/read.h b/include/picrin/read.h
index c77398e3..18d46ff7 100644
--- a/include/picrin/read.h
+++ b/include/picrin/read.h
@@ -2,8 +2,8 @@
  * See Copyright Notice in picrin.h
  */
 
-#ifndef PICRIN_READ_H__
-#define PICRIN_READ_H__
+#ifndef PICRIN_READ_H
+#define PICRIN_READ_H
 
 #if defined(__cplusplus)
 extern "C" {
diff --git a/include/picrin/string.h b/include/picrin/string.h
index 5a224d3d..325bec11 100644
--- a/include/picrin/string.h
+++ b/include/picrin/string.h
@@ -2,8 +2,8 @@
  * See Copyright Notice in picrin.h
  */
 
-#ifndef PICRIN_STRING_H__
-#define PICRIN_STRING_H__
+#ifndef PICRIN_STRING_H
+#define PICRIN_STRING_H
 
 #if defined(__cplusplus)
 extern "C" {
diff --git a/include/picrin/util.h b/include/picrin/util.h
index f2f5e719..d56cd9f6 100644
--- a/include/picrin/util.h
+++ b/include/picrin/util.h
@@ -2,8 +2,8 @@
  * See Copyright Notice in picrin.h
  */
 
-#ifndef PICRIN_UTIL_H__
-#define PICRIN_UTIL_H__
+#ifndef PICRIN_UTIL_H
+#define PICRIN_UTIL_H
 
 #if defined(__cplusplus)
 extern "C" {
@@ -20,12 +20,12 @@ extern "C" {
 #define FALLTHROUGH ((void)0)
 #define UNUSED(v) ((void)(v))
 
-#define GENSYM2__(x,y) G##x##_##y##__
-#define GENSYM1__(x,y) GENSYM2__(x,y)
+#define GENSYM2_(x,y) G##x##_##y##__
+#define GENSYM1_(x,y) GENSYM2_(x,y)
 #if defined(__COUNTER__)
-# define GENSYM(x) GENSYM1__(__COUNTER__,x)
+# define GENSYM(x) GENSYM1_(__COUNTER__,x)
 #else
-# define GENSYM(x) GENSYM1__(__LINE__,x)
+# define GENSYM(x) GENSYM1_(__LINE__,x)
 #endif
 
 #if GCC_VERSION >= 40500 || __clang__
@@ -36,8 +36,8 @@ extern "C" {
 #endif
 
 #define SWAP(type,a,b)                          \
-  SWAP_HELPER__(type,GENSYM(tmp),a,b)
-#define SWAP_HELPER__(type,tmp,a,b)             \
+  SWAP_HELPER_(type,GENSYM(tmp),a,b)
+#define SWAP_HELPER_(type,tmp,a,b)             \
   do {                                          \
     type tmp = (a);                             \
     (a) = (b);                                  \
diff --git a/include/picrin/value.h b/include/picrin/value.h
index dc8c6297..560e578a 100644
--- a/include/picrin/value.h
+++ b/include/picrin/value.h
@@ -2,8 +2,8 @@
  * See Copyright Notice in picrin.h
  */
 
-#ifndef PICRIN_VALUE_H__
-#define PICRIN_VALUE_H__
+#ifndef PICRIN_VALUE_H
+#define PICRIN_VALUE_H
 
 #if defined(__cplusplus)
 extern "C" {
diff --git a/include/picrin/var.h b/include/picrin/var.h
index 556647a8..4c1ba7c5 100644
--- a/include/picrin/var.h
+++ b/include/picrin/var.h
@@ -2,8 +2,8 @@
  * See Copyright Notice in picrin.h
  */
 
-#ifndef PICRIN_VAR_H__
-#define PICRIN_VAR_H__
+#ifndef PICRIN_VAR_H
+#define PICRIN_VAR_H
 
 #if defined(__cplusplus)
 extern "C" {
diff --git a/include/picrin/vector.h b/include/picrin/vector.h
index d4e54da9..514ecb4b 100644
--- a/include/picrin/vector.h
+++ b/include/picrin/vector.h
@@ -2,8 +2,8 @@
  * See Copyright Notice in picrin.h
  */
 
-#ifndef PICRIN_VECTOR_H__
-#define PICRIN_VECTOR_H__
+#ifndef PICRIN_VECTOR_H
+#define PICRIN_VECTOR_H
 
 #if defined(__cplusplus)
 extern "C" {