Index: sys/kern/kern_jail.c
===================================================================
--- sys/kern/kern_jail.c
+++ sys/kern/kern_jail.c
@@ -3141,16 +3141,16 @@
 }
 
 /*
- * Return 1 if p2 is a child of p1, otherwise 0.
+ * Return true if p2 is a child of p1, otherwise false.
  */
-int
+bool
 prison_ischild(struct prison *pr1, struct prison *pr2)
 {
 
 	for (pr2 = pr2->pr_parent; pr2 != NULL; pr2 = pr2->pr_parent)
 		if (pr1 == pr2)
-			return (1);
-	return (0);
+			return (true);
+	return (false);
 }
 
 /*
@@ -3185,21 +3185,21 @@
 }
 
 /*
- * Return 1 if the passed credential is in a jail and that jail does not
- * have its own virtual network stack, otherwise 0.
+ * Return true if the passed credential is in a jail and that jail does not
+ * have its own virtual network stack, otherwise false.
  */
-int
+bool
 jailed_without_vnet(struct ucred *cred)
 {
 
 	if (!jailed(cred))
-		return (0);
+		return (false);
 #ifdef VIMAGE
 	if (prison_owns_vnet(cred))
-		return (0);
+		return (false);
 #endif
 
-	return (1);
+	return (true);
 }
 
 /*
@@ -3261,9 +3261,9 @@
  * Determine whether the prison represented by cred owns
  * its vnet rather than having it inherited.
  *
- * Returns 1 in case the prison owns the vnet, 0 otherwise.
+ * Returns true in case the prison owns the vnet, false otherwise.
  */
-int
+bool
 prison_owns_vnet(struct ucred *cred)
 {
 
@@ -3271,7 +3271,7 @@
 	 * vnets cannot be added/removed after jail creation,
 	 * so no need to lock here.
 	 */
-	return (cred->cr_prison->pr_flags & PR_VNET ? 1 : 0);
+	return (cred->cr_prison->pr_flags & PR_VNET ? true : false);
 }
 #endif
 
Index: sys/sys/jail.h
===================================================================
--- sys/sys/jail.h
+++ sys/sys/jail.h
@@ -404,7 +404,7 @@
  */
 #define jailed(cred)	(cred->cr_prison != &prison0)
 
-int jailed_without_vnet(struct ucred *);
+bool jailed_without_vnet(struct ucred *);
 void getcredhostname(struct ucred *, char *, size_t);
 void getcreddomainname(struct ucred *, char *, size_t);
 void getcredhostuuid(struct ucred *, char *, size_t);
@@ -413,7 +413,7 @@
 void prison0_init(void);
 int prison_allow(struct ucred *, unsigned);
 int prison_check(struct ucred *cred1, struct ucred *cred2);
-int prison_owns_vnet(struct ucred *);
+bool prison_owns_vnet(struct ucred *);
 int prison_canseemount(struct ucred *cred, struct mount *mp);
 void prison_enforce_statfs(struct ucred *cred, struct mount *mp,
     struct statfs *sp);
@@ -428,7 +428,7 @@
 void prison_proc_hold(struct prison *);
 void prison_proc_free(struct prison *);
 void prison_set_allow(struct ucred *cred, unsigned flag, int enable);
-int prison_ischild(struct prison *, struct prison *);
+bool prison_ischild(struct prison *, struct prison *);
 bool prison_isalive(struct prison *);
 bool prison_isvalid(struct prison *);
 int prison_equal_ip4(struct prison *, struct prison *);