diff --git a/src/core/PieceTable.cc b/src/core/PieceTable.cc
index cfce928..c230879 100644
--- a/src/core/PieceTable.cc
+++ b/src/core/PieceTable.cc
@@ -345,10 +345,10 @@ void PieceTable::insertion_test(Cursor & c)
     m_append_buffer[m_append_buffer_index++] = 'z';
 
     Change * change = &m_changes_buffer[m_changes_buffer_index++];
-    change->prior_link[0][0] = c.iterator.piece->prev;
-    change->prior_link[0][1] = c.iterator.piece;
-    change->prior_link[1][0] = c.iterator.piece;
-    change->prior_link[1][1] = c.iterator.piece->next;
+    change->links[0][0][0] = c.iterator.piece->prev;
+    change->links[0][0][1] = c.iterator.piece;
+    change->links[0][1][0] = c.iterator.piece;
+    change->links[0][1][1] = c.iterator.piece->next;
 
     if (c.iterator.valid())
     {
@@ -369,49 +369,56 @@ void PieceTable::insertion_test(Cursor & c)
             piece->next = piece3;
             piece3->prev = piece;
 
-            change->new_link[0][0] = c.iterator.piece->prev;
-            change->new_link[0][1] = piece2;
-            change->new_link[1][0] = piece3;
-            change->new_link[1][1] = c.iterator.piece->next;
+            change->links[1][0][0] = c.iterator.piece->prev;
+            change->links[1][0][1] = piece2;
+            change->links[1][1][0] = piece3;
+            change->links[1][1][1] = c.iterator.piece->next;
         }
         else
         {
             if (c.iterator.piece->length == 0u)
             {
                 piece->flags = c.iterator.piece->flags;
-                change->new_link[0][0] = c.iterator.piece->prev;
-                change->new_link[0][1] = piece;
-                change->new_link[1][0] = piece;
-                change->new_link[1][1] = c.iterator.piece->next;
+                change->links[1][0][0] = c.iterator.piece->prev;
+                change->links[1][0][1] = piece;
+                change->links[1][1][0] = piece;
+                change->links[1][1][1] = c.iterator.piece->next;
             }
             else
             {
-                change->new_link[0][0] = c.iterator.piece->prev;
-                change->new_link[0][1] = piece;
-                change->new_link[1][0] = piece;
-                change->new_link[1][1] = c.iterator.piece;
+                change->links[1][0][0] = c.iterator.piece->prev;
+                change->links[1][0][1] = piece;
+                change->links[1][1][0] = piece;
+                change->links[1][1][1] = c.iterator.piece;
             }
         }
     }
     else
     {
-        change->new_link[0][0] = start_piece;
-        change->new_link[0][1] = piece;
-        change->new_link[1][0] = piece;
-        change->new_link[1][1] = end_piece;
+        change->links[1][0][0] = start_piece;
+        change->links[1][0][1] = piece;
+        change->links[1][1][0] = piece;
+        change->links[1][1][1] = end_piece;
     }
 
-    apply_change(change, 0u);
+    apply_change(change, 1u);
 
     c.warp_to_inserted_piece(piece);
 }
 
-void PieceTable::apply_change(Change * change, uint8_t reverse)
+void PieceTable::undo()
 {
-    uint8_t i1 = reverse;
-    uint8_t i2 = reverse ^ 1u;
-    change->new_link[i1][i1]->next = change->new_link[i1][i2];
-    change->new_link[i1][i2]->prev = change->new_link[i1][i1];
-    change->new_link[i2][i1]->next = change->new_link[i2][i2];
-    change->new_link[i2][i2]->prev = change->new_link[i2][i1];
+    if (m_changes_buffer_index > 0u)
+    {
+        m_changes_buffer_index--;
+        apply_change(&m_changes_buffer[m_changes_buffer_index], 0u);
+    }
+}
+
+void PieceTable::apply_change(Change * change, uint8_t forward)
+{
+    change->links[forward][0][0]->next = change->links[forward][0][1];
+    change->links[forward][0][1]->prev = change->links[forward][0][0];
+    change->links[forward][1][0]->next = change->links[forward][1][1];
+    change->links[forward][1][1]->prev = change->links[forward][1][0];
 }
diff --git a/src/core/PieceTable.h b/src/core/PieceTable.h
index e9cdde2..9c9494c 100644
--- a/src/core/PieceTable.h
+++ b/src/core/PieceTable.h
@@ -134,8 +134,7 @@ public:
 
     struct Change
     {
-        Piece * prior_link[2][2];
-        Piece * new_link[2][2];
+        Piece * links[2][2][2];
         bool insert;
     };
 
@@ -164,7 +163,9 @@ public:
 
     void insertion_test(Cursor & c);
 
-    void apply_change(Change * change, uint8_t reverse);
+    void undo();
+
+    void apply_change(Change * change, uint8_t forward);
 
 protected:
     const uint8_t * m_file_buffer;
diff --git a/src/gui/Window.cc b/src/gui/Window.cc
index 1c04338..25adc7f 100644
--- a/src/gui/Window.cc
+++ b/src/gui/Window.cc
@@ -270,6 +270,10 @@ void Window::handle_key(uint32_t scancode, uint32_t mod)
     case SDL_SCANCODE_P:
         insertion_test();
         break;
+    case SDL_SCANCODE_U:
+        m_buffer->piece_table->undo();
+        redraw();
+        break;
     }
 }