diff --git a/src/grid/mod.rs b/src/grid/mod.rs
index 1889d59f..23ee9cf4 100644
--- a/src/grid/mod.rs
+++ b/src/grid/mod.rs
@@ -236,8 +236,11 @@ impl<T: Copy + Clone> Grid<T> {
             self.raw.rotate_up(*positions);
 
             // Now, restore any scroll region lines
-            for i in IndexRange(region.end .. self.num_lines()) {
+            let lines = self.lines;
+            for i in IndexRange(region.end .. lines) {
                 // First do the swap
+                // TODO there is a bug here causing a panic.
+                // TODO math
                 self.raw.swap_lines(i, i + positions);
             }
 
diff --git a/src/grid/storage.rs b/src/grid/storage.rs
index b4228687..0ca2f525 100644
--- a/src/grid/storage.rs
+++ b/src/grid/storage.rs
@@ -69,6 +69,7 @@ impl<T> Storage<T> {
     }
 
     pub fn swap_lines(&mut self, a: Line, b: Line) {
+        println!("visible: {}, a: {}, b: {}", self.visible_lines, a, b);
         let a = self.visible_lines - a;
         let b = self.visible_lines - b;
         self.swap(*a, *b);