diff --git a/hw/kdrive/ephyr/ephyr_glamor_glx.c b/hw/kdrive/ephyr/ephyr_glamor_glx.c
index d56907fe7..eaf565496 100644
--- a/hw/kdrive/ephyr/ephyr_glamor_glx.c
+++ b/hw/kdrive/ephyr/ephyr_glamor_glx.c
@@ -67,6 +67,9 @@ struct ephyr_glamor {
     GLuint texture_shader;
     GLuint texture_shader_position_loc;
     GLuint texture_shader_texcoord_loc;
+
+    /* Size of the window that we're rendering to. */
+    unsigned width, height;
 };
 
 static GLint
@@ -205,6 +208,7 @@ ephyr_glamor_damage_redisplay(struct ephyr_glamor *glamor,
 
     glBindFramebuffer(GL_FRAMEBUFFER, 0);
     glUseProgram(glamor->texture_shader);
+    glViewport(0, 0, glamor->width, glamor->height);
 
     glVertexAttribPointer(glamor->texture_shader_position_loc,
                           2, GL_FLOAT, FALSE, 0, position);
@@ -329,3 +333,14 @@ ephyr_glamor_get_visual(void)
 
     return xcb_aux_find_visual_by_id(xscreen, visual_info->visualid);
 }
+
+void
+ephyr_glamor_set_window_size(struct ephyr_glamor *glamor,
+                             unsigned width, unsigned height)
+{
+    if (!glamor)
+        return;
+
+    glamor->width = width;
+    glamor->height = height;
+}
diff --git a/hw/kdrive/ephyr/ephyr_glamor_glx.h b/hw/kdrive/ephyr/ephyr_glamor_glx.h
index 8995e1eca..0c238cf5b 100644
--- a/hw/kdrive/ephyr/ephyr_glamor_glx.h
+++ b/hw/kdrive/ephyr/ephyr_glamor_glx.h
@@ -50,6 +50,10 @@ void
 ephyr_glamor_glx_screen_fini(struct ephyr_glamor *glamor);
 
 #ifdef GLAMOR
+void
+ephyr_glamor_set_window_size(struct ephyr_glamor *glamor,
+                             unsigned width, unsigned height);
+
 void
 ephyr_glamor_damage_redisplay(struct ephyr_glamor *glamor,
                               struct pixman_region16 *damage);
@@ -59,6 +63,12 @@ ephyr_glamor_process_event(xcb_generic_event_t *xev);
 
 #else /* !GLAMOR */
 
+static inline void
+ephyr_glamor_set_window_size(struct ephyr_glamor *glamor,
+                             unsigned width, unsigned height)
+{
+}
+
 static inline void
 ephyr_glamor_damage_redisplay(struct ephyr_glamor *glamor,
                               struct pixman_region16 *damage)
diff --git a/hw/kdrive/ephyr/hostx.c b/hw/kdrive/ephyr/hostx.c
index 859becaa6..0a9eb4696 100644
--- a/hw/kdrive/ephyr/hostx.c
+++ b/hw/kdrive/ephyr/hostx.c
@@ -731,6 +731,8 @@ hostx_screen_init(KdScreenInfo *screen,
     if (ephyr_glamor) {
         *bytes_per_line = 0;
         *bits_per_pixel = 0;
+        ephyr_glamor_set_window_size(scrpriv->glamor,
+                                     scrpriv->win_width, scrpriv->win_height);
         return NULL;
     } else if (host_depth_matches_server(scrpriv)) {
         *bytes_per_line = scrpriv->ximg->stride;
@@ -1218,6 +1220,8 @@ ephyr_glamor_init(ScreenPtr screen)
     EphyrScrPriv *scrpriv = kd_screen->driver;
 
     scrpriv->glamor = ephyr_glamor_glx_screen_init(scrpriv->win);
+    ephyr_glamor_set_window_size(scrpriv->glamor,
+                                 scrpriv->win_width, scrpriv->win_height);
 
     glamor_init(screen,
                 GLAMOR_USE_SCREEN |