diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index 1b08595768..bb2e8d133f 100644
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,3 +1,7 @@
+2019-07-15  Tom Tromey  <tromey@adacore.com>
+
+	* mi/mi-out.c (mi_ui_out::do_field_int): Use plongest.
+
 2019-07-15  Tom Tromey  <tromey@adacore.com>
 
 	* mi/mi-out.h (class mi_ui_out) <do_field_unsigned>: Declare.
diff --git a/gdb/mi/mi-out.c b/gdb/mi/mi-out.c
index dd99a2b7fb..75e3f0313d 100644
--- a/gdb/mi/mi-out.c
+++ b/gdb/mi/mi-out.c
@@ -98,10 +98,7 @@ void
 mi_ui_out::do_field_int (int fldno, int width, ui_align alignment,
 			 const char *fldname, int value)
 {
-  char buffer[20];	/* FIXME: how many chars long a %d can become? */
-
-  xsnprintf (buffer, sizeof (buffer), "%d", value);
-  do_field_string (fldno, width, alignment, fldname, buffer,
+  do_field_string (fldno, width, alignment, fldname, plongest (value),
 		   ui_out_style_kind::DEFAULT);
 }