diff --git a/.travis.yml b/.travis.yml
index 5448bfb..c67d9e0 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -6,7 +6,7 @@ env:
 
 language: nix
 
-script: nix-build --argstr compiler "$GHCVERSION" --arg doTracing "$TRACING"
+script: nix-build --argstr compiler "$GHCVERSION" --arg doTracing "$TRACING" --arg doStrict true
 
 notifications:
   webhooks:
diff --git a/default.nix b/default.nix
index 5d3473b..12cb725 100644
--- a/default.nix
+++ b/default.nix
@@ -2,6 +2,7 @@
 , doProfiling ? false
 , doBenchmark ? false
 , doTracing   ? false
+, doStrict    ? false
 , rev         ? "255a833e841628c0b834575664eae373e28cdc27"
 , sha256      ? "022xm1pf4fpjjy69g7qz6rpqnwpjcy1l0vj49m8xmgn553cs42ch"
 # , nixpkgs     ? import ((import <nixpkgs> {}).fetchFromGitHub {
@@ -54,8 +55,8 @@ in haskellPackages.developPackage {
 
     inherit doBenchmark;
 
-    configureFlags = if doTracing
-                     then [ "--flags=tracing" ]
-                     else [];
+    configureFlags =
+         pkgs.stdenv.lib.optional doTracing "--flags=tracing"
+      ++ pkgs.stdenv.lib.optional doStrict  "--ghc-options=-Werror"
   });
 }
diff --git a/hnix.cabal b/hnix.cabal
index 095f3c1..c4b17bf 100644
--- a/hnix.cabal
+++ b/hnix.cabal
@@ -2,7 +2,7 @@
 --
 -- see: https://github.com/sol/hpack
 --
--- hash: 0ae6db7ef792f86593ae6684bf7ab48b8e79cc147213ef6ab88475c142f9507a
+-- hash: 2d4def0d5852f7a3abefc681e54cdc16973060c9356c2c16e4f4c37b91c2e911
 
 name:           hnix
 version:        0.5.0
@@ -76,7 +76,7 @@ library
       Paths_hnix
   hs-source-dirs:
       src
-  ghc-options: -Wall -Werror
+  ghc-options: -Wall
   build-depends:
       aeson
     , ansi-wl-pprint
@@ -129,7 +129,7 @@ executable hnix
       Paths_hnix
   hs-source-dirs:
       main
-  ghc-options: -Wall -Werror
+  ghc-options: -Wall
   build-depends:
       aeson
     , ansi-wl-pprint
@@ -167,7 +167,7 @@ test-suite hnix-tests
       Paths_hnix
   hs-source-dirs:
       tests
-  ghc-options: -Wall -Werror -threaded
+  ghc-options: -Wall -threaded
   build-depends:
       Glob
     , ansi-wl-pprint
@@ -207,7 +207,7 @@ benchmark hnix-benchmarks
       Paths_hnix
   hs-source-dirs:
       benchmarks
-  ghc-options: -Wall -Werror
+  ghc-options: -Wall
   build-depends:
       ansi-wl-pprint
     , base >=4.9 && <5
diff --git a/package.yaml b/package.yaml
index 43c7197..84a966f 100644
--- a/package.yaml
+++ b/package.yaml
@@ -33,7 +33,6 @@ dependencies:
 
 ghc-options:
   - -Wall
-  - -Werror
 
 flags:
   tracing: