diff --git a/src/v_draw.cpp b/src/v_draw.cpp
index 2fa1e493e..bc17656fb 100644
--- a/src/v_draw.cpp
+++ b/src/v_draw.cpp
@@ -1086,6 +1086,15 @@ void DCanvas::Clear (int left, int top, int right, int bottom, int palcolor, uin
 	assert(left < right);
 	assert(top < bottom);
 
+	if (left >= Width || right <= 0 || top >= Height || bottom <= 0)
+	{
+		return;
+	}
+	left = MAX(0,left);
+	right = MIN(Width,right);
+	top = MAX(0,top);
+	bottom = MIN(Height,bottom);
+
 	if (palcolor < 0)
 	{
 		if (APART(color) != 255)
diff --git a/src/v_video.cpp b/src/v_video.cpp
index db0be3696..f2436862b 100644
--- a/src/v_video.cpp
+++ b/src/v_video.cpp
@@ -348,6 +348,23 @@ void DCanvas::Dim (PalEntry color, float damount, int x1, int y1, int w, int h)
 	BYTE *spot;
 	int x, y;
 
+	if (x1 >= Width || y1 >= Height)
+	{
+		return;
+	}
+	if (x1 + w > Width)
+	{
+		w = Width - x1;
+	}
+	if (y1 + h > Height)
+	{
+		h = Height - y1;
+	}
+	if (w <= 0 || h <= 0)
+	{
+		return;
+	}
+
 	{
 		int amount;