diff --git a/libc/runtime/mman.internal.h b/libc/runtime/mman.internal.h
index 0af3bb84e..9f96ed695 100644
--- a/libc/runtime/mman.internal.h
+++ b/libc/runtime/mman.internal.h
@@ -26,8 +26,9 @@ struct mman {
                                                      or pixels (graphics) */
   unsigned short pc_video_height;        /* 0x1d2e — height in chars. (text)
                                                      or pixels (graphics) */
-  uint32_t pc_video_framebuffer;         /* 0x1d30 */
-  uint32_t pc_video_framebuffer_size;    /* 0x1d34 */
+  uint64_t pc_video_framebuffer;         /* 0x1d30 — physical address of
+                                                     video frame buffer */
+  uint64_t pc_video_framebuffer_size;    /* 0x1d38 */
 };
 
 COSMOPOLITAN_C_END_
diff --git a/libc/vga/rlinit-vga.S b/libc/vga/rlinit-vga.S
index 914b2a4fa..e61b6b438 100644
--- a/libc/vga/rlinit-vga.S
+++ b/libc/vga/rlinit-vga.S
@@ -66,6 +66,9 @@
 	movw	$25,mm+"struct mman::pc_video_height"
 	movl	$0xb8000,mm+"struct mman::pc_video_framebuffer"
 	movl	$0x8000,mm+"struct mman::pc_video_framebuffer_size"
+	xor	%eax,%eax
+	mov	%eax,mm+"struct mman::pc_video_framebuffer"+4
+	mov	%eax,mm+"struct mman::pc_video_framebuffer_size"+4
 	mov	$0x1003,%ax		# enable/disable VGA text blinking
 #ifdef VGA_USE_BLINK
 	mov	$1,%bx