diff --git a/fasta.cabal b/fasta.cabal
--- a/fasta.cabal
+++ b/fasta.cabal
@@ -10,7 +10,7 @@
 -- PVP summary:      +-+------- breaking API changes
 --                   | | +----- non-breaking API additions
 --                   | | | +--- code changes with no API change
-version:             0.9.0.0
+version:             0.10.0.0
 
 -- A short (one-line) description of the package.
 synopsis:            A simple, mindless parser for fasta files.
diff --git a/src/Data/Fasta/ByteString/Lazy/Parse.hs b/src/Data/Fasta/ByteString/Lazy/Parse.hs
--- a/src/Data/Fasta/ByteString/Lazy/Parse.hs
+++ b/src/Data/Fasta/ByteString/Lazy/Parse.hs
@@ -100,7 +100,7 @@
 anyButSpace :: A.Parser Char
 anyButSpace = do
     A.skipSpace
-    x <- A.letter_ascii
+    x <- A.anyChar
     A.skipSpace
     return x
 
diff --git a/src/Data/Fasta/ByteString/Parse.hs b/src/Data/Fasta/ByteString/Parse.hs
--- a/src/Data/Fasta/ByteString/Parse.hs
+++ b/src/Data/Fasta/ByteString/Parse.hs
@@ -98,7 +98,7 @@
 anyButSpace :: A.Parser Char
 anyButSpace = do
     A.skipSpace
-    x <- A.letter_ascii
+    x <- A.anyChar
     A.skipSpace
     return x
 
diff --git a/src/Data/Fasta/Text/Lazy/Parse.hs b/src/Data/Fasta/Text/Lazy/Parse.hs
--- a/src/Data/Fasta/Text/Lazy/Parse.hs
+++ b/src/Data/Fasta/Text/Lazy/Parse.hs
@@ -99,7 +99,7 @@
 anyButSpace :: A.Parser Char
 anyButSpace = do
     A.skipSpace
-    x <- A.letter
+    x <- A.anyChar
     A.skipSpace
     return x
 
diff --git a/src/Data/Fasta/Text/Parse.hs b/src/Data/Fasta/Text/Parse.hs
--- a/src/Data/Fasta/Text/Parse.hs
+++ b/src/Data/Fasta/Text/Parse.hs
@@ -97,7 +97,7 @@
 anyButSpace :: A.Parser Char
 anyButSpace = do
     A.skipSpace
-    x <- A.letter
+    x <- A.anyChar
     A.skipSpace
     return x