diff --git a/src/pextlib1.0/Pextlib.c b/src/pextlib1.0/Pextlib.c
index 1a5420c2be..a3329db477 100644
--- a/src/pextlib1.0/Pextlib.c
+++ b/src/pextlib1.0/Pextlib.c
@@ -187,6 +187,24 @@ void ui_debug(Tcl_Interp *interp, const char *format, ...) {
     va_end(va);
 }
 
+__attribute__((format(printf, 2, 3)))
+void ui_debug2(Tcl_Interp *interp, const char *format, ...) {
+    va_list va;
+
+    va_start(va, format);
+    ui_message(interp, "debug2", format, va);
+    va_end(va);
+}
+
+__attribute__((format(printf, 2, 3)))
+void ui_debug3(Tcl_Interp *interp, const char *format, ...) {
+    va_list va;
+
+    va_start(va, format);
+    ui_message(interp, "debug3", format, va);
+    va_end(va);
+}
+
 int StrsedCmd(ClientData clientData UNUSED, Tcl_Interp *interp, int objc, Tcl_Obj *CONST objv[])
 {
     char *pattern, *string, *res;
diff --git a/src/pextlib1.0/Pextlib.h b/src/pextlib1.0/Pextlib.h
index c57e77cb0e..eb5df82677 100644
--- a/src/pextlib1.0/Pextlib.h
+++ b/src/pextlib1.0/Pextlib.h
@@ -35,6 +35,8 @@ void ui_msg(Tcl_Interp *interp, const char *format, ...) __attribute__((format(p
 void ui_notice(Tcl_Interp *interp, const char *format, ...) __attribute__((format(printf, 2, 3)));
 void ui_info(Tcl_Interp *interp, const char *format, ...) __attribute__((format(printf, 2, 3)));
 void ui_debug(Tcl_Interp *interp, const char *format, ...) __attribute__((format(printf, 2, 3)));
+void ui_debug2(Tcl_Interp *interp, const char *format, ...) __attribute__((format(printf, 2, 3)));
+void ui_debug3(Tcl_Interp *interp, const char *format, ...) __attribute__((format(printf, 2, 3)));
 
 /* Mount point file system case-sensitivity caching infrastructure. */
 typedef struct _mount_cs_cache mount_cs_cache_t;
diff --git a/src/pextlib1.0/tests/system.tcl b/src/pextlib1.0/tests/system.tcl
index eabe57f6d9..04a46ca24b 100644
--- a/src/pextlib1.0/tests/system.tcl
+++ b/src/pextlib1.0/tests/system.tcl
@@ -12,6 +12,12 @@ set failures 0
 proc ui_debug {args} {
     # ignored
 }
+proc ui_debug2 {args} {
+    # ignored
+}
+proc ui_debug3 {args} {
+    # ignored
+}
 proc ui_info {args} {
     global output
     append output "$args\n"
diff --git a/src/port1.0/port.tcl b/src/port1.0/port.tcl
index 1ec2de33c7..b716171ce4 100644
--- a/src/port1.0/port.tcl
+++ b/src/port1.0/port.tcl
@@ -54,9 +54,9 @@ namespace eval port {
 	proc run_callbacks {} {
 		variable _callback_list
 		foreach callback ${_callback_list} {
-			ui_debug "Running callback ${callback}"
+			ui_debug2 "Running callback ${callback}"
 			${callback}
-			ui_debug "Finished running callback ${callback}"
+			ui_debug2 "Finished running callback ${callback}"
 		}
 		set _callback_list [list]
 	}