diff --git a/doc/indevs.texi b/doc/indevs.texi
index 92bc65be41..e2a3540203 100644
--- a/doc/indevs.texi
+++ b/doc/indevs.texi
@@ -1532,7 +1532,7 @@ ffmpeg -f x11grab -follow_mouse centered -show_region 1 -framerate 25 -video_siz
 @end example
 
 @item video_size
-Set the video frame size. Default value is @code{vga}.
+Set the video frame size. Default is the full desktop.
 
 @item grab_x
 @item grab_y
diff --git a/libavdevice/version.h b/libavdevice/version.h
index 68302908cf..ec0ba776be 100644
--- a/libavdevice/version.h
+++ b/libavdevice/version.h
@@ -29,7 +29,7 @@
 
 #define LIBAVDEVICE_VERSION_MAJOR  58
 #define LIBAVDEVICE_VERSION_MINOR   9
-#define LIBAVDEVICE_VERSION_MICRO 101
+#define LIBAVDEVICE_VERSION_MICRO 102
 
 #define LIBAVDEVICE_VERSION_INT AV_VERSION_INT(LIBAVDEVICE_VERSION_MAJOR, \
                                                LIBAVDEVICE_VERSION_MINOR, \
diff --git a/libavdevice/xcbgrab.c b/libavdevice/xcbgrab.c
index 861eef07b5..113cce71a5 100644
--- a/libavdevice/xcbgrab.c
+++ b/libavdevice/xcbgrab.c
@@ -70,7 +70,6 @@ typedef struct XCBGrabContext {
     int region_border;
     int centered;
 
-    const char *video_size;
     const char *framerate;
 
     int has_shm;
@@ -85,7 +84,7 @@ static const AVOption options[] = {
     { "y", "Initial y coordinate.", OFFSET(y), AV_OPT_TYPE_INT, { .i64 = 0 }, 0, INT_MAX, D },
     { "grab_x", "Initial x coordinate.", OFFSET(x), AV_OPT_TYPE_INT, { .i64 = 0 }, 0, INT_MAX, D },
     { "grab_y", "Initial y coordinate.", OFFSET(y), AV_OPT_TYPE_INT, { .i64 = 0 }, 0, INT_MAX, D },
-    { "video_size", "A string describing frame size, such as 640x480 or hd720.", OFFSET(video_size), AV_OPT_TYPE_STRING, {.str = "vga" }, 0, 0, D },
+    { "video_size", "A string describing frame size, such as 640x480 or hd720.", OFFSET(width), AV_OPT_TYPE_IMAGE_SIZE, {.str = NULL }, 0, 0, D },
     { "framerate", "", OFFSET(framerate), AV_OPT_TYPE_STRING, {.str = "ntsc" }, 0, 0, D },
     { "draw_mouse", "Draw the mouse pointer.", OFFSET(draw_mouse), AV_OPT_TYPE_INT, { .i64 = 1 }, 0, 1, D },
     { "follow_mouse", "Move the grabbing region when the mouse pointer reaches within specified amount of pixels to the edge of region.",
@@ -555,10 +554,6 @@ static int create_stream(AVFormatContext *s)
     if (!st)
         return AVERROR(ENOMEM);
 
-    ret = av_parse_video_size(&c->width, &c->height, c->video_size);
-    if (ret < 0)
-        return ret;
-
     ret = av_parse_video_rate(&st->avg_frame_rate, c->framerate);
     if (ret < 0)
         return ret;
@@ -570,6 +565,11 @@ static int create_stream(AVFormatContext *s)
     if (!geo)
         return AVERROR_EXTERNAL;
 
+    if (!c->width || !c->height) {
+        c->width = geo->width;
+        c->height = geo->height;
+    }
+
     if (c->x + c->width > geo->width ||
         c->y + c->height > geo->height) {
         av_log(s, AV_LOG_ERROR,