diff --git a/lib/libutil/Symbol.map b/lib/libutil/Symbol.map
--- a/lib/libutil/Symbol.map
+++ b/lib/libutil/Symbol.map
@@ -115,7 +115,6 @@
 	setclassenvironment;
 	setclassresources;
 	setusercontext;
-	trimdomain;
 	uu_lock_txfr;
 	uu_lock;
 	uu_lockerr;
@@ -130,6 +129,10 @@
 	crypt_set_format;
 };
 
+FBSD_1.9 {
+	trimdomain;
+};
+
 FBSDprivate_1.0 {
 	__pw_initpwd;
 };
diff --git a/lib/libutil/libutil.h b/lib/libutil/libutil.h
--- a/lib/libutil/libutil.h
+++ b/lib/libutil/libutil.h
@@ -140,7 +140,7 @@
 int	realhostname_sa(char *_host, size_t _hsize, struct sockaddr *_addr,
 	    int _addrlen);
 int	_secure_path(const char *_path, uid_t _uid, gid_t _gid);
-void	trimdomain(char *_fullhost, int _hostsize);
+void	trimdomain(char *_fullhost, size_t _hostsize);
 const char *
 	uu_lockerr(int _uu_lockresult);
 int	uu_lock(const char *_ttyname);
diff --git a/lib/libutil/trimdomain.3 b/lib/libutil/trimdomain.3
--- a/lib/libutil/trimdomain.3
+++ b/lib/libutil/trimdomain.3
@@ -22,7 +22,7 @@
 .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 .\" SUCH DAMAGE.
 .\"
-.Dd April 7, 1999
+.Dd January 9, 2026
 .Dt TRIMDOMAIN 3
 .Os
 .Sh NAME
@@ -34,7 +34,7 @@
 .In sys/types.h
 .In libutil.h
 .Ft void
-.Fn trimdomain "char *fullhost" "int hostsize"
+.Fn trimdomain "char *fullhost" "size_t hostsize"
 .Sh DESCRIPTION
 The function
 .Fn trimdomain
@@ -53,13 +53,13 @@
 The
 .Fn trimdomain
 function will only trim the domain name if the passed
-.Ar fullname
+.Ar fullhost
 ends with the current domain name and if the length of the resulting host
 name does not exceed
 .Ar hostsize .
 .Pp
 If the passed
-.Ar fullname
+.Ar fullhost
 is actually a
 .Dv DISPLAY
 specification of the form
diff --git a/lib/libutil/trimdomain.c b/lib/libutil/trimdomain.c
--- a/lib/libutil/trimdomain.c
+++ b/lib/libutil/trimdomain.c
@@ -34,6 +34,7 @@
 #include <string.h>
 #include <unistd.h>
 
+void		freebsd15_trimdomain(char *, int);
 static int	isDISP(const char *);
 
 /*-
@@ -50,7 +51,7 @@
  *     trimdomain("abcde.my.domain:0.0", 8)   ->   "abcde.my.domain:0.0"
  */
 void
-trimdomain(char *fullhost, int hostsize)
+trimdomain(char *fullhost, size_t hostsize)
 {
 	static size_t dlen;
 	static int first = 1;
@@ -89,6 +90,14 @@
 	}
 }
 
+void
+freebsd15_trimdomain(char *fullhost, int hostsize)
+{
+	trimdomain(fullhost, hostsize);
+}
+
+__sym_compat(trimdomain, freebsd15_trimdomain, FBSD_1.8);
+
 /*
  * Is the given string NN or NN.NN where ``NN'' is an all-numeric string ?
  */