diff --git a/net-misc/mbpoll/mbpoll-1.5.2.ebuild b/net-misc/mbpoll/mbpoll-1.5.2.ebuild
index 30d654f8af..134348fc27 100644
--- a/net-misc/mbpoll/mbpoll-1.5.2.ebuild
+++ b/net-misc/mbpoll/mbpoll-1.5.2.ebuild
@@ -15,3 +15,10 @@ KEYWORDS="~amd64"
 
 DEPEND="dev-libs/libmodbus"
 RDEPEND="${DEPEND}"
+
+src_prepare() {
+	sed -i -e 's/add_definitions(-O2)//' CMakeLists.txt
+	sed -i -e 's/-O2 //' CMakeLists.txt
+
+	cmake_src_prepare
+}
diff --git a/net-misc/mbpoll/mbpoll-9999.ebuild b/net-misc/mbpoll/mbpoll-9999.ebuild
index 85fefda9fd..18a20b4220 100644
--- a/net-misc/mbpoll/mbpoll-9999.ebuild
+++ b/net-misc/mbpoll/mbpoll-9999.ebuild
@@ -14,3 +14,10 @@ SLOT="0"
 
 DEPEND="dev-libs/libmodbus"
 RDEPEND="${DEPEND}"
+
+src_prepare() {
+	sed -i -e 's/add_definitions(-O2)//' CMakeLists.txt
+	sed -i -e 's/-O2 //' CMakeLists.txt
+
+	cmake_src_prepare
+}