diff --git a/dist-build/msys2-win32.sh b/dist-build/msys2-win32.sh
index bbe7b11a..513b8e49 100755
--- a/dist-build/msys2-win32.sh
+++ b/dist-build/msys2-win32.sh
@@ -1,6 +1,7 @@
 #! /bin/sh
 
-export CFLAGS="-O3 -fomit-frame-pointer -m32 -march=pentium3 -mtune=westmere"
+export CFLAGS="-Ofast -fomit-frame-pointer -m32 -march=pentium3 -mtune=westmere"
+export LDFLAGS="-m32 -march=pentium3 -flto"
 export PREFIX="$(pwd)/libsodium-win32"
 
 make distclean > /dev/null
diff --git a/dist-build/msys2-win64.sh b/dist-build/msys2-win64.sh
index 43f0b697..de5c1a14 100755
--- a/dist-build/msys2-win64.sh
+++ b/dist-build/msys2-win64.sh
@@ -1,6 +1,7 @@
 #! /bin/sh
 
-export CFLAGS="-O3 -fomit-frame-pointer -m64 -mtune=westmere"
+export CFLAGS="-Ofast -fomit-frame-pointer -m64 -mtune=westmere -flto"
+export LDFLAGS="-m64 -flto"
 export PREFIX="$(pwd)/libsodium-win64"
 
 make distclean > /dev/null