diff --git a/liblists/lists.h b/liblists/lists.h
index 6643552..982c8bc 100644
--- a/liblists/lists.h
+++ b/liblists/lists.h
@@ -32,7 +32,7 @@
 #ifndef __cplusplus
 #ifndef PETIDOMO_HAS_DEFINED_BOOL
 #  define PETIDOMO_HAS_DEFINED_BOOL 1
-typedef int bool;
+#include <stdbool.h>
 #endif
 #ifndef FALSE
 #  define FALSE (0==1)
diff --git a/libtext/text.h b/libtext/text.h
index a258c79..1fd5274 100644
--- a/libtext/text.h
+++ b/libtext/text.h
@@ -36,7 +36,7 @@ extern "C" {
 #ifndef __cplusplus
 #ifndef PETIDOMO_HAS_DEFINED_BOOL
 #  define PETIDOMO_HAS_DEFINED_BOOL 1
-typedef int bool;
+#include <stdbool.h>
 #endif
 
 #ifndef FALSE
diff --git a/petidomo.h b/petidomo.h
index d503de0..a0c1308 100644
--- a/petidomo.h
+++ b/petidomo.h
@@ -26,7 +26,7 @@
 
 #ifndef PETIDOMO_HAS_DEFINED_BOOL
 #    define PETIDOMO_HAS_DEFINED_BOOL 1
-     typedef int bool;
+#include <stdbool.h>
 #endif
 
 #ifndef DEBUG_DMALLOC
@@ -135,7 +135,7 @@ struct Mail
     };
 
 void RemoveCarrigeReturns(char *buffer);
-int isRFC822Address(const char *buffer);
+bool isRFC822Address(const char *buffer);
 int ParseAddressLine(char *buffer);
 int ParseReplyToLine(char *buffer);
 int ParseFromLine(char *buffer);
@@ -157,8 +157,8 @@ int ArchiveMail(const struct Mail *MailStruct, const char *listname);
 /********** authen.c **********/
 
 int FindBodyPassword(struct Mail *MailStruct);
-int isValidAdminPassword(const char *password, const char *listname);
-int isValidPostingPassword(const char *password, const char *listname);
+bool isValidAdminPassword(const char *password, const char *listname);
+bool isValidPostingPassword(const char *password, const char *listname);
 
 /********** filter.c **********/
 
@@ -226,7 +226,7 @@ const char *getPassword(void  );
 /********** tool.c **********/
 
 char *buildFuzzyMatchAddress(const char *);
-int isValidListName(const char *);
+bool isValidListName(const char *);
 bool isSubscribed(const char *, const char *, char **, char **, bool);
 
 /********** unsubscribe.c **********/