diff --git a/configure.ac b/configure.ac
index 76aa6dde..b226921e 100644
--- a/configure.ac
+++ b/configure.ac
@@ -133,7 +133,24 @@ AS_CASE(["$host_os"],
     )
 )
 
-AC_CHECK_HEADERS(execinfo.h pty.h util.h zlib.h bzlib.h libutil.h sys/ttydefaults.h x86intrin.h)
+AC_CHECK_HEADERS(execinfo.h pty.h util.h zlib.h bzlib.h libutil.h sys/ttydefaults.h)
+
+dnl Experimental SIMD features.
+AC_ARG_ENABLE([simd],
+    AS_HELP_STRING([--enable-simd], [Try and enable simd optimizations]),
+    [
+     AS_CASE(["$enable_simd"],
+             [no], [enable_simd="no"],
+             [yes | ""],[enable_simd="yes"])
+     ],
+     []
+)
+
+AS_IF([test "x$enable_simd" = "xyes"], [
+       AC_CHECK_HEADERS(x86intrin.h)
+])
+
+
 
 LNAV_WITH_JEMALLOC
 
diff --git a/release/vagrant-static/build.sh b/release/vagrant-static/build.sh
index 4f6ddbd9..1674a753 100755
--- a/release/vagrant-static/build.sh
+++ b/release/vagrant-static/build.sh
@@ -46,7 +46,7 @@ if test x"${OS}" != x"FreeBSD"; then
         TARGET_FILE='/vagrant/lnav-musl.zip'
         ../lnav/configure \
             CFLAGS='-static -no-pie -s' \
-            CXXFLAGS='-static -msse4 -U__unused -no-pie -s' \
+            CXXFLAGS='-static -U__unused -no-pie -s' \
             LDFLAGS="-L${FAKE_ROOT}/lib" \
             CPPFLAGS="-I${FAKE_ROOT}/include" \
             --enable-static
diff --git a/src/line_buffer.cc b/src/line_buffer.cc
index e227a624..6a0241cf 100644
--- a/src/line_buffer.cc
+++ b/src/line_buffer.cc
@@ -655,7 +655,6 @@ Result<line_info, string> line_buffer::load_next_line(file_range prev_line)
         /* ... look for the end-of-line or end-of-file. */
         ssize_t utf8_end = -1;
 
-#undef HAVE_X86INTRIN_H
 #ifdef HAVE_X86INTRIN_H
         if (!validate_utf8_fast(line_start, retval.li_file_range.fr_size, &utf8_end)) {
             retval.li_valid_utf = false;