diff --git a/ChangeLog.md b/ChangeLog.md
--- a/ChangeLog.md
+++ b/ChangeLog.md
@@ -1,5 +1,9 @@
 <!-- -*- Markdown -*- -->
 
+## 0.9.0.1
+
+- Use Haskell implementation test instead of flag test in .cabal
+
 ## 0.9.0.0
 
 - Add HRR instances of tuple types derived by generic programming.
diff --git a/relational-query.cabal b/relational-query.cabal
--- a/relational-query.cabal
+++ b/relational-query.cabal
@@ -1,5 +1,5 @@
 name:                relational-query
-version:             0.9.0.0
+version:             0.9.0.1
 synopsis:            Typeful, Modular, Relational, algebraic query engine
 description:         This package contiains typeful relation structure and
                      relational-algebraic query building DSL which can
@@ -25,10 +25,6 @@
                      , GHC == 7.4.1, GHC == 7.4.2
 extra-source-files:  ChangeLog.md
 
-flag ghc74-generic
-  description: Enable for generic programming using old ghc. If true use ghc-prim.
-  default:     False
-
 library
   exposed-modules:
                        Database.Relational.Query.Arrow
@@ -97,7 +93,7 @@
                        , sql-words >=0.1.4
                        , names-th
                        , persistable-record >= 0.5
-  if flag(ghc74-generic)
+  if impl(ghc == 7.4.*)
     build-depends:        ghc-prim == 0.2.*
 
   hs-source-dirs:      src
@@ -111,7 +107,7 @@
                        , relational-query
                        , containers
                        , transformers
-  if flag(ghc74-generic)
+  if impl(ghc == 7.4.*)
     build-depends:        ghc-prim == 0.2.*
 
   type:                exitcode-stdio-1.0
@@ -131,7 +127,7 @@
                        , relational-query
                        , containers
                        , transformers
-  if flag(ghc74-generic)
+  if impl(ghc == 7.4.*)
     build-depends:        ghc-prim == 0.2.*
 
   type:                exitcode-stdio-1.0