--- a/ed25519.cabal
+++ b/ed25519.cabal
@@ -130,7 +130,7 @@ test-suite doctests
       base      >= 4    && < 5,
       filepath  >= 1.0  && < 1.5,
       directory >= 1.0  && < 1.4,
-      doctest   >= 0.10 && < 0.12
+      doctest   >= 0.10 && < 0.19
 
 -------------------------------------------------------------------------------
 -- Build pt 3: benchmarks
