diff --git a/runtime/include/gpu_vk_renderer.h b/runtime/include/gpu_vk_renderer.h
index 47820fa8..7b09ea66 100644
--- a/runtime/include/gpu_vk_renderer.h
+++ b/runtime/include/gpu_vk_renderer.h
@@ -52,6 +52,7 @@ void vk_renderer_restage_vram_after_savestate(void);
  * -1=MAILBOX. Tear-free prefers MAILBOX because the frontend already paces
  * frames; unsupported modes fall back to FIFO (always available). */
 void vk_renderer_set_present_mode(int mode);
+void vk_renderer_set_display_aspect(int num, int den);
 
 #ifdef __cplusplus
 }
diff --git a/runtime/src/gpu_vk_renderer.c b/runtime/src/gpu_vk_renderer.c
index cf85ebac..7ac92f3d 100644
--- a/runtime/src/gpu_vk_renderer.c
+++ b/runtime/src/gpu_vk_renderer.c
@@ -44,6 +44,7 @@ void vk_renderer_present_blank(void){}
 void vk_renderer_sync_cpu(void){}
 void vk_renderer_restage_vram_after_savestate(void){}
 void vk_renderer_set_present_mode(int m){(void)m;}
+void vk_renderer_set_display_aspect(int n,int d){(void)n;(void)d;}
 int  vk_perf_json(char *out,int cap,int count){(void)count; return cap>2?snprintf(out,cap,"[]"):0;}
 const GpuRenderBackend *vk_backend_get(void) { return 0; }
 
@@ -63,6 +64,13 @@ const GpuRenderBackend *vk_backend_get(void) { return 0; }
 #define VRAM_W 1024
 #define VRAM_H 512
 
+static int s_aspect_num = 4, s_aspect_den = 3;
+
+void vk_renderer_set_display_aspect(int num, int den) {
+    if (num <= 0 || den <= 0) { num = 4; den = 3; }
+    s_aspect_num = num; s_aspect_den = den;
+}
+
 /* ---- dynamic loader ---------------------------------------------------- */
 /* vkGetInstanceProcAddr comes from SDL; everything else is loaded through it
  * (global/instance scope) or vkGetDeviceProcAddr (device scope). */
@@ -1690,7 +1698,7 @@ int vk_renderer_present_vram(int disp_x, int disp_y, int w, int h,
 
     VkOffset3D dst[2];
     letterbox((int)s_sc_extent.width, (int)s_sc_extent.height,
-              force_4_3 ? 4 : 4, force_4_3 ? 3 : 3, dst);
+              force_4_3 ? 4 : s_aspect_num, force_4_3 ? 3 : s_aspect_den, dst);
 
     VkImageBlit blit = {0};
     blit.srcSubresource.aspectMask = VK_IMAGE_ASPECT_COLOR_BIT;
@@ -1799,7 +1807,7 @@ void vk_renderer_present_cpu(const uint32_t *pixels, int src_w, int src_h,
     p_vkCmdClearColorImage(cb, sc, VK_IMAGE_LAYOUT_TRANSFER_DST_OPTIMAL, &black, 1, &rng);
 
     VkOffset3D dst[2];
-    letterbox((int)s_sc_extent.width, (int)s_sc_extent.height, 4, 3, dst);
+    letterbox((int)s_sc_extent.width, (int)s_sc_extent.height, force_4_3 ? 4 : s_aspect_num, force_4_3 ? 3 : s_aspect_den, dst);
     /* Short GP1(07h) bands: letterbox inside the 4:3 rect (see GL present). */
     if (src_h > 0 && src_h < 240) {
         int box_h = dst[1].y - dst[0].y;
diff --git a/runtime/src/main.cpp b/runtime/src/main.cpp
index 0ddf5740..5d61970a 100644
--- a/runtime/src/main.cpp
+++ b/runtime/src/main.cpp
@@ -1743,6 +1743,7 @@ static void update_adaptive_widescreen() {
     g_video_aspect_num = num;
     g_video_aspect_den = den;
     gl_renderer_set_display_aspect(num, den);
+    vk_renderer_set_display_aspect(num, den);
     if (sdl_renderer) {
         g_logical_w = 480 * num * g_video_scale / den;
         SDL_RenderSetLogicalSize(sdl_renderer, g_logical_w, 480 * g_video_scale);
@@ -14505,6 +14506,7 @@ session_reboot:
      * this aspect; native-wide fills it with a genuinely wider frame (no
      * stretch), squash mode stretches the 4:3 frame into it. */
     gl_renderer_set_display_aspect(g_video_aspect_num, g_video_aspect_den);
+    vk_renderer_set_display_aspect(g_video_aspect_num, g_video_aspect_den);
     if (g_video_aspect_num * 3 != g_video_aspect_den * 4) {
         /* Hold widescreen off through the BIOS boot (authentic 4:3 logos);
          * the per-frame present path engages it at game entry. */