diff -up flac-1.3.2/configure.ac.cflags flac-1.3.2/configure.ac
--- flac-1.3.2/configure.ac.cflags	2017-01-02 14:02:15.663046237 +0100
+++ flac-1.3.2/configure.ac	2017-01-02 14:04:20.718046015 +0100
@@ -390,7 +390,7 @@ if test "x$debug" = xtrue; then
 else
 	CPPFLAGS="-DNDEBUG $CPPFLAGS"
 	CFLAGS=$(echo "$CFLAGS" | sed 's/-O2//')
-	CFLAGS="-O3 -funroll-loops $CFLAGS"
+	CFLAGS="$user_cflags"
 fi
 
 XIPH_GCC_VERSION
@@ -400,7 +400,6 @@ if test x$ac_cv_c_compiler_gnu = xyes ;
 	CXXFLAGS="$CXXFLAGS -Wall -Wextra -Wcast-align -Wshadow -Wwrite-strings -Wctor-dtor-privacy -Wnon-virtual-dtor -Wreorder -Wsign-promo -Wundef " # -Wcast-qual -Wbad-function-cast -Wwrite-strings -Woverloaded-virtual -Wmissing-declarations
 
 	XIPH_ADD_CFLAGS([-Wdeclaration-after-statement])
-	XIPH_ADD_CFLAGS([-D_FORTIFY_SOURCE=2])
 
 	AC_LANG_PUSH([C++])
 	XIPH_ADD_CXXFLAGS([-Weffc++])
@@ -426,10 +425,6 @@ if test x$ac_cv_c_compiler_gnu = xyes ;
 		XIPH_ADD_CFLAGS([-fno-inline-small-functions])
 		fi
 
-	if test "x$asm_optimisation$sse_os" = "xyesyes" ; then
-		XIPH_ADD_CFLAGS([-msse2])
-		fi
-
 	fi
 
 case "$host_os" in