diff --git a/modules/video_output/opengl/sub_renderer.c b/modules/video_output/opengl/sub_renderer.c
index 82bc8ae936..fb3550b57d 100644
--- a/modules/video_output/opengl/sub_renderer.c
+++ b/modules/video_output/opengl/sub_renderer.c
@@ -68,6 +68,7 @@ struct vlc_gl_sub_renderer
 
     gl_region_t *regions;
     unsigned region_count;
+    unsigned output_width, output_height;
 
     GLuint program_id;
     struct {
@@ -130,6 +131,8 @@ vlc_gl_sub_renderer_New(vlc_gl_t *gl, const struct vlc_gl_api *api,
     sr->api = api;
     sr->vt = vt;
     sr->region_count = 0;
+    sr->output_width = 0;
+    sr->output_height = 0;
     sr->regions = NULL;
 
     static const char *const VERTEX_SHADER_SRC =
@@ -223,12 +226,23 @@ vlc_gl_sub_renderer_Delete(struct vlc_gl_sub_renderer *sr)
     free(sr);
 }
 
+void
+vlc_gl_sub_renderer_SetOutputSize(struct vlc_gl_sub_renderer *sr,
+                                  unsigned width, unsigned height)
+{
+    sr->output_width = width;
+    sr->output_height = height;
+}
+
 int
 vlc_gl_sub_renderer_Prepare(struct vlc_gl_sub_renderer *sr,
                             const vlc_render_subpicture *subpicture)
 {
     GL_ASSERT_NOERROR(sr->vt);
 
+    if (unlikely(sr->output_width == 0 || sr->output_height == 0))
+        return VLC_EINVAL;
+
     const struct vlc_gl_interop *interop = sr->interop;
 
     int last_count = sr->region_count;
@@ -261,10 +275,10 @@ vlc_gl_sub_renderer_Prepare(struct vlc_gl_sub_renderer *sr,
                 glr->tex_height = 1.0;
             }
             glr->alpha  = (float)r->i_alpha / 255;
-            glr->left   =  2.0 * (r->place.x                  ) / subpicture->i_original_picture_width  - 1.0;
-            glr->top    = -2.0 * (r->place.y                  ) / subpicture->i_original_picture_height + 1.0;
-            glr->right  =  2.0 * (r->place.x + r->place.width ) / subpicture->i_original_picture_width  - 1.0;
-            glr->bottom = -2.0 * (r->place.y + r->place.height) / subpicture->i_original_picture_height + 1.0;
+            glr->left   =  2.0 * (r->place.x                  ) / sr->output_width  - 1.0;
+            glr->top    = -2.0 * (r->place.y                  ) / sr->output_height + 1.0;
+            glr->right  =  2.0 * (r->place.x + r->place.width ) / sr->output_width  - 1.0;
+            glr->bottom = -2.0 * (r->place.y + r->place.height) / sr->output_height + 1.0;
 
             glr->texture = 0;
             /* Try to recycle the textures allocated by the previous
diff --git a/modules/video_output/opengl/sub_renderer.h b/modules/video_output/opengl/sub_renderer.h
index b255b1c1ac..edec795d3e 100644
--- a/modules/video_output/opengl/sub_renderer.h
+++ b/modules/video_output/opengl/sub_renderer.h
@@ -72,6 +72,13 @@ int
 vlc_gl_sub_renderer_Prepare(struct vlc_gl_sub_renderer *sr,
                             const struct vlc_render_subpicture *subpicture);
 
+/**
+ * Change the output size
+ */
+void
+vlc_gl_sub_renderer_SetOutputSize(struct vlc_gl_sub_renderer *sr,
+                                  unsigned width, unsigned height);
+
 /**
  * Draw the prepared subpicture
  *
diff --git a/modules/video_output/opengl/vout_helper.c b/modules/video_output/opengl/vout_helper.c
index 354ac7af22..15e2a7c792 100644
--- a/modules/video_output/opengl/vout_helper.c
+++ b/modules/video_output/opengl/vout_helper.c
@@ -358,6 +358,7 @@ void vout_display_opengl_SetOutputSize(vout_display_opengl_t *vgl,
     /* The renderer, last filter in the chain, necessarily accepts the new
      * output size */
     assert(ret == VLC_SUCCESS);
+    vlc_gl_sub_renderer_SetOutputSize(vgl->sub_renderer, width, height);
     (void) ret;
 }
 
diff --git a/test/modules/video_output/opengl/sub_renderer.c b/test/modules/video_output/opengl/sub_renderer.c
index 89dcd55ebd..5297edaf9b 100644
--- a/test/modules/video_output/opengl/sub_renderer.c
+++ b/test/modules/video_output/opengl/sub_renderer.c
@@ -173,6 +173,8 @@ static void test_opengl_offscreen(
     memcpy(&picture->p[0].p_pixels[0 * 4 + picture->p[0].i_pitch], blue, sizeof(blue));
     memcpy(&picture->p[0].p_pixels[1 * 4 + picture->p[0].i_pitch], white, sizeof(white));
 
+    vlc_gl_sub_renderer_SetOutputSize(sr, 4, 4);
+
     vlc_render_subpicture *subpicture = vlc_render_subpicture_New();
     assert(subpicture != NULL);
     subpicture->i_original_picture_width = 4;