diff --git a/dev-haskell/sha/sha-1.6.4.2.ebuild b/dev-haskell/sha/sha-1.6.4.2.ebuild
index c1c37c05ab7ff..e796c590c23c0 100644
--- a/dev-haskell/sha/sha-1.6.4.2.ebuild
+++ b/dev-haskell/sha/sha-1.6.4.2.ebuild
@@ -19,9 +19,11 @@ SRC_URI="mirror://hackage/packages/archive/${MY_PN}/${PV}/${MY_P}.tar.gz"
 
 LICENSE="BSD"
 SLOT="0/${PV}"
-KEYWORDS="~amd64 ~x86 ~amd64-linux"
+KEYWORDS="amd64 x86 ~amd64-linux"
 IUSE="exe"
 
+RESTRICT=test # fails to build on ghc-7.6, https://ghc.haskell.org/trac/ghc/ticket/8657
+
 RDEPEND=">=dev-haskell/binary-0.7:=[profile?] <dev-haskell/binary-10000:=[profile?]
 	>=dev-lang/ghc-7.4.1:=
 "
@@ -34,6 +36,11 @@ DEPEND="${RDEPEND}
 
 S="${WORKDIR}/${MY_P}"
 
+src_prepare() {
+	cabal_chdeps \
+		' -O2' ' '
+}
+
 src_configure() {
 	haskell-cabal_src_configure \
 		--flag=decoderinterface \