diff --git a/waflib/ConfigSet.py b/waflib/ConfigSet.py
index 4047c4a7..79775d9b 100644
--- a/waflib/ConfigSet.py
+++ b/waflib/ConfigSet.py
@@ -6,7 +6,7 @@
 
 ConfigSet: a special dict
 
-The values put in :py:class:`ConfigSet` must be lists
+The values put in :py:class:`ConfigSet` must be serializable (dicts, lists, strings)
 """
 
 import copy, re, os
diff --git a/waflib/Errors.py b/waflib/Errors.py
index 104f7d82..e5ffe44a 100644
--- a/waflib/Errors.py
+++ b/waflib/Errors.py
@@ -35,9 +35,7 @@ class WafError(Exception):
 		return str(self.msg)
 
 class BuildError(WafError):
-	"""
-	Errors raised during the build and install phases
-	"""
+	"""Error raised during the build and install phases"""
 	def __init__(self, error_tasks=[]):
 		"""
 		:param error_tasks: tasks that could not complete normally
@@ -47,7 +45,7 @@ class BuildError(WafError):
 		WafError.__init__(self, self.format_error())
 
 	def format_error(self):
-		"""format the error messages from the tasks that failed"""
+		"""Formats the error messages from the tasks that failed"""
 		lst = ['Build failed']
 		for tsk in self.tasks:
 			txt = tsk.format_error()
@@ -55,16 +53,14 @@ class BuildError(WafError):
 		return '\n'.join(lst)
 
 class ConfigurationError(WafError):
-	"""
-	Configuration exception raised in particular by :py:meth:`waflib.Context.Context.fatal`
-	"""
+	"""Configuration exception raised in particular by :py:meth:`waflib.Context.Context.fatal`"""
 	pass
 
 class TaskRescan(WafError):
-	"""task-specific exception type, trigger a signature recomputation"""
+	"""Task-specific exception type signalling required signature recalculations"""
 	pass
 
 class TaskNotReady(WafError):
-	"""task-specific exception type, raised when the task signature cannot be computed"""
+	"""Task-specific exception type signalling that task signatures cannot be computed"""
 	pass