diff --git a/include/picrin/parse.h b/include/picrin/parse.h
new file mode 100644
index 00000000..6eff8d62
--- /dev/null
+++ b/include/picrin/parse.h
@@ -0,0 +1,14 @@
+#ifndef PARSE_H__
+#define PARSE_H__
+
+struct parser_control {
+  pic_state *pic;
+  void *yyscanner;
+  pic_value value;
+  bool incomp;
+  int yynerrs;
+  struct pic_vector *yy_arena;
+  int yy_arena_idx;
+};
+
+#endif
diff --git a/src/parse.y b/src/parse.y
index b14f5626..00bf58a2 100644
--- a/src/parse.y
+++ b/src/parse.y
@@ -6,6 +6,7 @@
 #include "picrin.h"
 #include "picrin/pair.h"
 #include "picrin/blob.h"
+#include "picrin/parse.h"
 
 #define YYERROR_VERBOSE 1
 
@@ -17,16 +18,6 @@ void yyset_in();
 void yy_scan_string();
 void yylex_destroy();
 
-struct parser_control {
-  pic_state *pic;
-  void *yyscanner;
-  pic_value value;
-  bool incomp;
-  int yynerrs;
-  struct pic_vector *yy_arena;
-  int yy_arena_idx;
-};
-
 #define YY_ARENA_SIZE 50
 
 struct parser_control *
diff --git a/src/scan.l b/src/scan.l
index 7e7e4700..a24da8ab 100644
--- a/src/scan.l
+++ b/src/scan.l
@@ -3,10 +3,7 @@
 #include <string.h>
 
 #include "picrin.h"
-
-/* Guts! bison3 seems emit prototype declaration of yyparse in y.tab.h... */
-struct parser_control;
-
+#include "picrin/parse.h"
 #include "y.tab.h"
 
 #define YY_DECL int yylex_(YYSTYPE *yylvalp, yyscan_t yyscanner)