diff --git a/Vec-Transform.cabal b/Vec-Transform.cabal
--- a/Vec-Transform.cabal
+++ b/Vec-Transform.cabal
@@ -1,5 +1,5 @@
 name: Vec-Transform
-version: 1.0.1
+version: 1.0.2
 cabal-version: >=1.2.3
 build-type: Simple
 license: BSD3
diff --git a/src/Data/Vec/LinAlg/Transform3D.hs b/src/Data/Vec/LinAlg/Transform3D.hs
--- a/src/Data/Vec/LinAlg/Transform3D.hs
+++ b/src/Data/Vec/LinAlg/Transform3D.hs
@@ -119,7 +119,7 @@
                                            0, 0, -(f+n)/(f-n), -2*f*n/(f-n),
                                            0,0,-1,0]
     where
-        t = 2*n*tan(fovy/2)
+        t = n*tan(fovy/2)
         b = -t
         r = aspect*t
         l = -r