diff --git a/ion/src/simulator/init.cpp b/ion/src/simulator/init.cpp
index 612f007bf..a449dae66 100644
--- a/ion/src/simulator/init.cpp
+++ b/ion/src/simulator/init.cpp
@@ -22,14 +22,19 @@ static FltkKbd * sKeyboard;
 
 void init_platform() {
   Fl::visual(FL_RGB);
+
   int margin = 10;
+  int screen_width = FRAMEBUFFER_WIDTH;
+  int screen_height = FRAMEBUFFER_HEIGHT;
+  // keyboard_width == screen_width
+  int keyboard_height = screen_width;
 
-  Fl_Window * window = new Fl_Window(FRAMEBUFFER_WIDTH+2*margin, FRAMEBUFFER_HEIGHT+2*margin+120+2*margin);
+  Fl_Window * window = new Fl_Window(screen_width+2*margin, margin+screen_height+margin+keyboard_height+margin);
 
-  sDisplay = new FltkLCD(margin, margin, FRAMEBUFFER_WIDTH, FRAMEBUFFER_HEIGHT);
+  sDisplay = new FltkLCD(margin, margin, screen_width, screen_height);
   assert(FRAMEBUFFER_BITS_PER_PIXEL == 8);
 
-  sKeyboard = new FltkKbd(margin,FRAMEBUFFER_HEIGHT+3*margin,FRAMEBUFFER_WIDTH,120);
+  sKeyboard = new FltkKbd(margin, margin+screen_height+margin, screen_width, keyboard_height);
 
   window->end();
   window->show(NULL, NULL);
diff --git a/ion/src/simulator/keyboard/fltkkbd.cpp b/ion/src/simulator/keyboard/fltkkbd.cpp
index 16a82857b..a9cf4d81e 100644
--- a/ion/src/simulator/keyboard/fltkkbd.cpp
+++ b/ion/src/simulator/keyboard/fltkkbd.cpp
@@ -1,8 +1,15 @@
+#include <assert.h>
 #include "fltkkbd.h"
 
+#define KEYBOARD_ROWS 7
+#define KEYBOARD_COLUMNS 5
+
 FltkKbd::FltkKbd(int x, int y, int w, int h) : Fl_Group(x, y, w, h) {
+  assert(KEYBOARD_ROWS*KEYBOARD_COLUMNS == ION_NUMBER_OF_KEYS);
+  int key_width = w/KEYBOARD_COLUMNS;
+  int key_height = h/KEYBOARD_ROWS;
   for (int k=0; k<ION_NUMBER_OF_KEYS; k++) {
-    m_buttons[k] = new Fl_Button(x+(k*w)/ION_NUMBER_OF_KEYS, y, w/ION_NUMBER_OF_KEYS, h);
+    m_buttons[k] = new Fl_Button(x + (k%KEYBOARD_COLUMNS)*key_width, y + (k/KEYBOARD_COLUMNS)*key_height, key_width, key_height);
   }
   end();
 }