diff --git a/Emux.GameBoy/Cartridge/CartridgeType.cs b/Emux.GameBoy/Cartridge/CartridgeType.cs
index a197c41..beebbc2 100644
--- a/Emux.GameBoy/Cartridge/CartridgeType.cs
+++ b/Emux.GameBoy/Cartridge/CartridgeType.cs
@@ -1,7 +1,8 @@
-using System.Collections;
-
-namespace Emux.GameBoy.Cartridge
+namespace Emux.GameBoy.Cartridge
 {
+    /// <summary>
+    /// Provides a collection of valid (but not necessarily supported) cartridge types.
+    /// </summary>
     public enum CartridgeType : byte
     {
         RomOnly = 0x00,
diff --git a/Emux.GameBoy/Cpu/InterruptFlags.cs b/Emux.GameBoy/Cpu/InterruptFlags.cs
index 2557da4..daf2e26 100644
--- a/Emux.GameBoy/Cpu/InterruptFlags.cs
+++ b/Emux.GameBoy/Cpu/InterruptFlags.cs
@@ -2,6 +2,9 @@
 
 namespace Emux.GameBoy.Cpu
 {
+    /// <summary>
+    /// Provides valid interrupt flags used by the interrupt registers IF and IE.
+    /// </summary>
     [Flags]
     public enum InterruptFlags : byte
     {
diff --git a/Emux.GameBoy/Graphics/GameBoyGpu.cs b/Emux.GameBoy/Graphics/GameBoyGpu.cs
index 8eb59bf..f50d213 100644
--- a/Emux.GameBoy/Graphics/GameBoyGpu.cs
+++ b/Emux.GameBoy/Graphics/GameBoyGpu.cs
@@ -258,7 +258,7 @@ namespace Emux.GameBoy.Graphics
                         {
                             _modeClock -= HBlankCycles;
                             LY++;
-                            if (LY >= FrameHeight - 1)
+                            if (LY == FrameHeight - 1)
                             {
                                 currentMode = LcdStatusFlags.VBlankMode;
                                 VideoOutput.RenderFrame(_frameBuffer);