diff --git a/hasql-transaction.cabal b/hasql-transaction.cabal
--- a/hasql-transaction.cabal
+++ b/hasql-transaction.cabal
@@ -1,7 +1,7 @@
 name:
   hasql-transaction
 version:
-  0.5
+  0.5.1
 category:
   Hasql, Database, PostgreSQL
 synopsis:
@@ -53,7 +53,7 @@
     Hasql.Transaction.Sessions
   build-depends:
     -- database:
-    hasql >= 0.17 && < 0.20,
+    hasql >= 0.17 && < 0.20 || >= 1 && < 1.1,
     -- data:
     bytestring-tree-builder >= 0.1 && < 0.3,
     bytestring >= 0.10 && < 0.11,
diff --git a/library/Hasql/Transaction/Private/Sessions.hs b/library/Hasql/Transaction/Private/Sessions.hs
--- a/library/Hasql/Transaction/Private/Sessions.hs
+++ b/library/Hasql/Transaction/Private/Sessions.hs
@@ -7,6 +7,11 @@
 import qualified Hasql.Transaction.Private.Queries as B
 
 
+{-
+We may want to
+do one transaction retry in case of the 23505 error, and fail if an identical
+error is seen.
+-}
 inRetryingTransaction :: IsolationLevel -> Mode -> A.Session (a, Bool) -> A.Session a
 inRetryingTransaction isolation mode session =
   fix $ \recur -> catchError normal (onError recur)