diff --git a/mathmech/CMakeLists.txt b/mathmech/CMakeLists.txt
index 5e67fb7..2fd4155 100644
--- a/mathmech/CMakeLists.txt
+++ b/mathmech/CMakeLists.txt
@@ -46,7 +46,7 @@ if ( CMAKE_COMPILER_IS_GNUCXX )
   set (ADD_CXX_FLAGS  "-Wall")
   set (CMAKE_CXX_FLAGS "-O0 ${ADD_CXX_FLAGS}")
   set (CMAKE_CXX_FLAGS_DEBUG "-g -O0")
-  set (CMAKE_CXX_FLAGS_RELEASE "-O3 -DNDEBUG")
+  set (CMAKE_CXX_FLAGS_RELEASE "-O2 -DNDEBUG")
 elseif ( MSVC )
   set (ADD_CXX_FLAGS  "/W4")
   set (CMAKE_CXX_FLAGS "${ADD_CXX_FLAGS}")
@@ -67,4 +67,4 @@ endforeach ()
 # set docs file
 if (ADD_DOCS)
   include (docs.cmake)
-endif ()
\ No newline at end of file
+endif ()
diff --git a/mathmech/PKGBUILD b/mathmech/PKGBUILD
index 1a7f93e..ff770f5 100644
--- a/mathmech/PKGBUILD
+++ b/mathmech/PKGBUILD
@@ -11,7 +11,7 @@ license=('Beerware')
 depends=('qwt')
 makedepends=('cmake' 'automoc4')
 source=(https://github.com/arcan1s/moldyn/releases/download/mm-${pkgver}/${pkgname}-${pkgver}-src.zip)
-md5sums=('bc79faa2eba4e319286596569ec19882')
+md5sums=('de893eee2230269b10099c5fd925502b')
 _cmakekeys="-DCMAKE_INSTALL_PREFIX=/usr
             -DQWT_INCLUDE_PATH=/usr/include/qwt
             -DQWT_LIBRARY_PATH=/usr/lib