diff --git a/graph-rewriting-ski.cabal b/graph-rewriting-ski.cabal
--- a/graph-rewriting-ski.cabal
+++ b/graph-rewriting-ski.cabal
@@ -1,5 +1,5 @@
 Name:           graph-rewriting-ski
-Version:        0.6.6
+Version:        0.6.7
 Copyright:      (c) 2010, Jan Rochel
 License:        BSD3
 License-File:   LICENSE
@@ -25,14 +25,14 @@
     FlexibleContexts
     MultiParamTypeClasses
   Build-Depends:
-    base >= 4.3 && < 5,
-    base-unicode-symbols >= 0.2,
+    base >= 4.3 && < 4.10,
+    base-unicode-symbols >= 0.2 && < 0.3,
     graph-rewriting >= 0.7.6,
     graph-rewriting-layout >= 0.5.4,
     graph-rewriting-gl >= 0.7.6,
-    parsec >= 3.1.0,
-    GLUT >= 2.4,
-    OpenGL >= 3.0
+    parsec >= 3.1.0 && < 3.2,
+    GLUT >= 2.4 && < 2.8,
+    OpenGL >= 3.0 && < 3.1
 
 Executable ski-direct
   Main-Is:        Direct/Main.hs