diff --git a/.travis.yml b/.travis.yml
index ebef63682..454d43e66 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -93,7 +93,7 @@ install:
 - |
   case "$BUILD" in
     stack)
-    stack --no-terminal --install-ghc $ARGS test --flag 'aeson:fast' --only-dependencies
+    stack --no-terminal --install-ghc $ARGS test --flag 'aeson:fast' --only-dependencies --fast
       ;;
     cabal)
       cabal --version
@@ -106,10 +106,10 @@ script:
 - |
   case "$BUILD" in
     stack)
-    stack --no-terminal $ARGS test --flag 'aeson:fast' --haddock --no-haddock-deps --ghc-options="-Wall -fno-warn-unused-do-bind -Werror"
+    stack --no-terminal $ARGS test --flag 'aeson:fast' --haddock --no-haddock-deps --ghc-options="-O0 -Wall -fno-warn-unused-do-bind -Werror"
       ;;
     cabal)
-      cabal configure --enable-tests --enable-benchmarks -v2 --ghc-options="-O0 -Werror"
+      cabal configure --enable-tests --enable-benchmarks -v2 -ffast --ghc-options="-O0 -Wall -fno-warn-unused-do-bind -Werror"
       cabal build
       cabal check
       cabal test