diff --git a/b2/boom.c b/b2/boom.c
index 86bf088..381dc47 100644
--- a/b2/boom.c
+++ b/b2/boom.c
@@ -12,29 +12,11 @@
 
 #include <stdlib.h>
 #include <stdio.h>
-#include <unistd.h>
 #include <string.h>
-#include <fcntl.h>
 
 #include "lang.h"
 
 
-static void open_stdin(const char *name)
-{
-	int fd;
-
-	fd = open(name, O_RDONLY);
-	if (fd < 0) {
-		perror(name);
-		exit(1);
-	}
-	if (dup2(fd, 0) < 0) {
-		perror("dup2");
-		exit(1);
-	}
-}
-
-
 static void usage(const char *name)
 {
 	fprintf(stderr,
@@ -51,7 +33,7 @@ static void usage(const char *name)
 
 int main(int argc, char **argv)
 {
-	void (*parse)(void) = parse_hierarchy;
+	void (*parse)(const char *name) = parse_hierarchy;
 	int i;
 
 	for (i = 1; i != argc; i++) {
@@ -67,8 +49,7 @@ int main(int argc, char **argv)
 			else
 				usage(*argv);
 		} else {
-			open_stdin(argv[i]);
-			parse();
+			parse(argv[i]);
 		}
 	}
 	return 0;
diff --git a/b2/lang.h b/b2/lang.h
index fe0f263..923ab9a 100644
--- a/b2/lang.h
+++ b/b2/lang.h
@@ -13,11 +13,11 @@
 #ifndef LANG_H
 #define	LANG_H
 
-void parse_hierarchy(void);
-void parse_characteristics(void);
-void parse_inventory(void);
-void parse_currencies(void);
-void parse_providers(void);
+void parse_hierarchy(const char *name);
+void parse_characteristics(const char *name);
+void parse_inventory(const char *name);
+void parse_currencies(const char *name);
+void parse_providers(const char *name);
 
 void yywarnf(const char *fmt, ...);
 void yyerrorf(const char *fmt, ...);
diff --git a/b2/lang.l b/b2/lang.l
index 1772ea3..6ef5581 100644
--- a/b2/lang.l
+++ b/b2/lang.l
@@ -12,6 +12,8 @@
 
 #include <stdarg.h>
 #include <stdlib.h>
+#include <unistd.h>
+#include <fcntl.h>
 
 #include "util.h"
 #include "param.h"
@@ -27,48 +29,59 @@ static int expose_nl;
 static int lineno;
 
 
-void parse_hierarchy(void)
+static void open_stdin(const char *name)
 {
-	start_token = START_HIERARCHY;
-	expose_nl = 0;
+	int fd;
+
+	fd = open(name, O_RDONLY);
+	if (fd < 0) {
+		perror(name);
+		exit(1);
+	}
+	if (dup2(fd, 0) < 0) {
+		perror("dup2");
+		exit(1);
+	}
+}
+
+
+static void do_parse(const char *name, int start, int nl)
+{
+	open_stdin(name);
+	start_token = start;
+	expose_nl = nl;
 	lineno = 1;
 	yyparse();
 }
 
 
-void parse_characteristics(void)
+void parse_hierarchy(const char *name)
 {
-	start_token = START_CHAR;
-	expose_nl = 1;
-	lineno = 1;
-	yyparse();
+	do_parse(name, START_HIERARCHY, 0);
 }
 
 
-void parse_inventory(void)
+void parse_characteristics(const char *name)
 {
-	start_token = START_INVENTORY;
-	expose_nl = 1;
-	lineno = 1;
-	yyparse();
+	do_parse(name, START_CHAR, 1);
 }
 
 
-void parse_currencies(void)
+void parse_inventory(const char *name)
 {
-	start_token = START_EXCHANGE;
-	expose_nl = 1;
-	lineno = 1;
-	yyparse();
+	do_parse(name, START_INVENTORY, 1);
 }
 
 
-void parse_providers(void)
+void parse_currencies(const char *name)
 {
-	start_token = START_PROVIDERS;
-	expose_nl = 1;
-	lineno = 1;
-	yyparse();
+	do_parse(name, START_EXCHANGE, 1);
+}
+
+
+void parse_providers(const char *name)
+{
+	do_parse(name, START_PROVIDERS, 1);
 }
 
 %}