diff --git a/cpu.c b/cpu.c
index d457868..f58d181 100644
--- a/cpu.c
+++ b/cpu.c
@@ -25,6 +25,7 @@
 	cpu->regs[SP] = 0xFD; // stack at is 0x100 + SP
 	cpu->pc = 0x600; // arbitrary program counter start
 	cpu->running = true;
+	memset(cpu->mem + 0x100, 0, 0xFE);
 }
 
 cpu_t new_cpu()
diff --git a/gui.c b/gui.c
index 201fdae..f9cd310 100644
--- a/gui.c
+++ b/gui.c
@@ -39,13 +39,9 @@
 		.b = 0.50f,
 		.a = 1.0f,
 	};
-	struct nk_color selected =
-	{
-		.r = 28,
-		.g = 234,
-		.b = 79,
-		.a = 255,
-	};
+	struct nk_color
+		selected = nk_rgb(28, 234, 79),
+		red = nk_rgb(226, 56, 76);
 
 	uint16_t disas_start = 0x600,
 		disas_end = 0x600 + 32;
@@ -162,6 +158,30 @@
 		}
 		nk_end(ctx);
 
+		if (nk_begin(ctx, "Stack", nk_rect(250, 250, 230, 350),
+			NK_WINDOW_BORDER|NK_WINDOW_MOVABLE|NK_WINDOW_SCALABLE|
+			NK_WINDOW_MINIMIZABLE|NK_WINDOW_TITLE))
+		{
+			nk_layout_row_static(ctx, 24, 48, 2);
+			for (int i = 0xFD; i >= 0; i--)
+			{
+				char line[6];
+				sprintf(line, "$%x", 0x100 + i);
+				nk_label(ctx, line, NK_TEXT_LEFT);
+
+				sprintf(line, "$%x", cpu->mem[0x100 + i]);
+				if (i == cpu->regs[SP])
+				{
+					nk_label_colored(ctx, line, NK_TEXT_LEFT, selected);
+				}
+				else
+				{
+					nk_label(ctx, line, NK_TEXT_LEFT);
+				}
+			}
+		}
+		nk_end(ctx);
+
 		if (nk_begin(ctx, "Debugger", nk_rect(50, 50, 230, 150),
 			NK_WINDOW_BORDER|NK_WINDOW_MOVABLE|NK_WINDOW_SCALABLE|
 			NK_WINDOW_MINIMIZABLE|NK_WINDOW_TITLE))