diff --git a/BizHawk.Client.EmuHawk/tools/NES/NESNameTableViewer.cs b/BizHawk.Client.EmuHawk/tools/NES/NESNameTableViewer.cs
index a8c8fb91af..083eb8c799 100644
--- a/BizHawk.Client.EmuHawk/tools/NES/NESNameTableViewer.cs
+++ b/BizHawk.Client.EmuHawk/tools/NES/NESNameTableViewer.cs
@@ -246,7 +246,10 @@ namespace BizHawk.Client.EmuHawk
 
 		private void NESNameTableViewer_FormClosed(object sender, FormClosedEventArgs e)
 		{
-			_ppu.RemoveCallback1();
+			if (_ppu != null)
+			{
+				_ppu.RemoveCallback1();
+			}
 		}
 
 		private void ScanlineTextbox_TextChanged(object sender, EventArgs e)
diff --git a/BizHawk.Client.EmuHawk/tools/NES/NESPPU.cs b/BizHawk.Client.EmuHawk/tools/NES/NESPPU.cs
index 59f9ebeb76..22412f45f6 100644
--- a/BizHawk.Client.EmuHawk/tools/NES/NESPPU.cs
+++ b/BizHawk.Client.EmuHawk/tools/NES/NESPPU.cs
@@ -799,7 +799,10 @@ namespace BizHawk.Client.EmuHawk
 
 		private void NesPPU_FormClosed(object sender, FormClosedEventArgs e)
 		{
-			_ppu.RemoveCallback2();
+			if (_ppu != null)
+			{
+				_ppu.RemoveCallback2();
+			}
 		}
 
 		#endregion