diff --git a/CHANGELOG.markdown b/CHANGELOG.markdown
--- a/CHANGELOG.markdown
+++ b/CHANGELOG.markdown
@@ -1,3 +1,7 @@
+1.13
+----
+* Switched 'ortho' to follow the OpenGL handedness.
+
 1.12.1
 ------
 * Added "swizzle" lenses **e.g.** `_yzx`, which are useful for working with libraries like `gl`.
diff --git a/linear.cabal b/linear.cabal
--- a/linear.cabal
+++ b/linear.cabal
@@ -1,6 +1,6 @@
 name:          linear
 category:      Math, Algebra
-version:       1.12.1
+version:       1.13
 license:       BSD3
 cabal-version: >= 1.8
 license-file:  LICENSE
diff --git a/src/Linear/Perspective.hs b/src/Linear/Perspective.hs
--- a/src/Linear/Perspective.hs
+++ b/src/Linear/Perspective.hs
@@ -93,9 +93,9 @@
   -> a -- ^ Far
   -> M44 a
 ortho left right bottom top near far =
-  V4 (V4 (2 / a) 0       0        (negate ((right + left) / a)))
-     (V4 0       (2 / b) 0        (negate ((top + bottom) / b)))
-     (V4 0       0       (-2 / c) ((far + near) / c))
+  V4 (V4 (2 / a) 0       0        (negate (right + left) / a))
+     (V4 0       (2 / b) 0        (negate (top + bottom) / b))
+     (V4 0       0       (-2 / c) (negate (far + near) / c))
      (V4 0       0       0        1)
   where a = right - left
         b = top - bottom