diff --git a/ChangeLog b/ChangeLog
index 5c6019fc..3758312e 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,6 +1,7 @@
 NEW IN WAF 2.0.0
 ----------------
-* Keep sorted lists in TaskGen.prec[]
+* Reverse the mappping in TaskGen.prec[]
+* Sort TaskGen methods besides regular constraints
 * Removed ut_fun from waf_unit_test.py
 * Force files into the build directory by default
 
diff --git a/docs/sphinx/conf.py b/docs/sphinx/conf.py
index 6dfd298f..2b1a96f0 100644
--- a/docs/sphinx/conf.py
+++ b/docs/sphinx/conf.py
@@ -98,8 +98,7 @@ def before(*k):
 		exclude_taskgen.append(func.__name__)
 		setattr(task_gen, func.__name__, func)
 		for fun_name in k:
-			if not func.__name__ in task_gen.prec[fun_name]:
-				task_gen.prec[fun_name].append(func.__name__)
+			task_gen.prec[func.__name__].add(fun_name)
 		fix_fun_doc(func)
 		append_doc(func, 'before', k)
 		return func
@@ -112,8 +111,7 @@ def after(*k):
 		exclude_taskgen.append(func.__name__)
 		setattr(task_gen, func.__name__, func)
 		for fun_name in k:
-			if not fun_name in task_gen.prec[func.__name__]:
-				task_gen.prec[func.__name__].append(fun_name)
+			task_gen.prec[fun_name].add(func.__name__)
 		fix_fun_doc(func)
 		append_doc(func, 'after', k)
 		return func