diff --git a/CHANGES b/CHANGES
--- a/CHANGES
+++ b/CHANGES
@@ -1,5 +1,10 @@
 API-ish changes in the hledger-lib package.
-(For user-visible changes, see hledger's change log.)
+See also the hledger and project change logs (for user-visible changes).
+
+
+# 1.0.1 (2016/10/27)
+
+- allow megaparsec 5.0 or 5.1
 
 
 # 1.0 (2016/10/26)
diff --git a/Hledger/Utils/Debug.hs b/Hledger/Utils/Debug.hs
--- a/Hledger/Utils/Debug.hs
+++ b/Hledger/Utils/Debug.hs
@@ -81,10 +81,12 @@
       args = unsafePerformIO getArgs
 
 -- | Convenience aliases for tracePrettyAt.
--- Pretty-print a message and the showable value to the console, then return it.
-dbg :: Show a => String -> a -> a
-dbg = tracePrettyAt 0
 
+-- Always pretty-print a message and the showable value to the console, then return it.
+-- ("dbg" without the 0 clashes with megaparsec 5.1).
+dbg0 :: Show a => String -> a -> a
+dbg0 = tracePrettyAt 0
+
 -- | Pretty-print a message and the showable value to the console when the debug level is >= 1, then return it. Uses unsafePerformIO.
 dbg1 :: Show a => String -> a -> a
 dbg1 = tracePrettyAt 1
@@ -212,7 +214,7 @@
 
 -- | Like dbg, then exit the program. Uses unsafePerformIO.
 dbgExit :: Show a => String -> a -> a
-dbgExit msg = const (unsafePerformIO exitFailure) . dbg msg
+dbgExit msg = const (unsafePerformIO exitFailure) . dbg0 msg
 
 -- | Print a message and parsec debug info (parse position and next
 -- input) to the console when the debug level is at or above
diff --git a/hledger-lib.cabal b/hledger-lib.cabal
--- a/hledger-lib.cabal
+++ b/hledger-lib.cabal
@@ -3,7 +3,7 @@
 -- see: https://github.com/sol/hpack
 
 name:           hledger-lib
-version:        1.0
+version:        1.0.1
 stability:      stable
 category:       Finance
 synopsis:       Core data types, parsers and functionality for the hledger accounting tools
@@ -68,7 +68,7 @@
     , deepseq
     , directory
     , filepath
-    , megaparsec >=5 && < 5.1
+    , megaparsec >=5.0 && < 5.2
     , mtl
     , mtl-compat
     , old-time
@@ -158,7 +158,7 @@
     , deepseq
     , directory
     , filepath
-    , megaparsec >=5 && < 5.1
+    , megaparsec >=5.0 && < 5.2
     , mtl
     , mtl-compat
     , old-time
@@ -198,7 +198,7 @@
     , deepseq
     , directory
     , filepath
-    , megaparsec >=5 && < 5.1
+    , megaparsec >=5.0 && < 5.2
     , mtl
     , mtl-compat
     , old-time