diff --git a/src/ios/iOSMiniFB.m b/src/ios/iOSMiniFB.m
index 9538291..0f9716b 100644
--- a/src/ios/iOSMiniFB.m
+++ b/src/ios/iOSMiniFB.m
@@ -3,6 +3,7 @@
 #include <mach/mach_time.h>
 
 #include "iOSViewController.h"
+#include "iOSViewDelegate.h"
 #include "WindowData_IOS.h"
 #include <MiniFB.h>
 #include <MiniFB_internal.h>
@@ -35,8 +36,7 @@ create_window_data(unsigned width, unsigned height) {
     window_data->window_width  = [UIScreen mainScreen].bounds.size.width  * scale;
     window_data->window_height = [UIScreen mainScreen].bounds.size.height * scale;
 
-    window_data->dst_width     = width;
-    window_data->dst_height    = height;
+    calc_dst_factor(window_data, width, height);
 
     window_data->buffer_width  = width;
     window_data->buffer_height = height;
@@ -191,6 +191,7 @@ mfb_set_viewport(struct mfb_window *window, unsigned offset_x, unsigned offset_y
     window_data->dst_offset_y = offset_y;
     window_data->dst_width    = width;
     window_data->dst_height   = height;
+    calc_dst_factor(window_data, window_data->window_width, window_data->window_height);
 
     float x1 =  ((float) offset_x           / window_data->window_width)  * 2.0f - 1.0f;
     float x2 = (((float) offset_x + width)  / window_data->window_width)  * 2.0f - 1.0f;
diff --git a/src/ios/iOSViewDelegate.m b/src/ios/iOSViewDelegate.m
index ff01a4f..1e6fb65 100644
--- a/src/ios/iOSViewDelegate.m
+++ b/src/ios/iOSViewDelegate.m
@@ -240,9 +240,12 @@ NSString *g_shader_src = kShader(
 
 //-------------------------------------
 - (void) mtkView:(nonnull MTKView *)view drawableSizeWillChange:(CGSize)size {
+    (void) view;
     // Respond to drawable size or orientation changes here
-    window_data->window_width  = size.width;
-    window_data->window_height = size.height;
+    float scale = [UIScreen mainScreen].scale;
+
+    window_data->window_width  = size.width  * scale;
+    window_data->window_height = size.height * scale;
     resize_dst(window_data, size.width, size.height);
 
     kCall(resize_func, size.width, size.height);
diff --git a/tests/ios/AppDelegate.m b/tests/ios/AppDelegate.m
index d10f2c0..26e03cd 100644
--- a/tests/ios/AppDelegate.m
+++ b/tests/ios/AppDelegate.m
@@ -43,6 +43,7 @@ resize(struct mfb_window *window, int width, int height) {
     kUnused(window);
     g_width  = width;
     g_height = height;
+    g_buffer = realloc(g_buffer, g_width * g_height * 4);
     NSLog(@"Resize %d, %d", width, height);
 }
 
@@ -95,6 +96,9 @@ resize(struct mfb_window *window, int width, int height) {
         g_height = [UIScreen mainScreen].bounds.size.height * g_scale;
         g_window = mfb_open("noise", g_width, g_height);
         if(g_window != 0x0) {
+            g_width  -= 100;
+            g_height -= 100;
+            mfb_set_viewport(g_window, 50, 50, g_width, g_height);
             g_buffer = malloc(g_width * g_height * 4);
             mfb_set_mouse_move_callback(g_window, mouse_move);
             mfb_set_mouse_button_callback(g_window, mouse_btn);