diff --git a/.gitignore b/.gitignore
index 9332c1488..e654f0206 100644
--- a/.gitignore
+++ b/.gitignore
@@ -40,6 +40,7 @@ tests/*.so
 tests/run-tests-*
 tests/last-random-state.lisp-expr
 tests/ansi-test/
+tools-for-build/avx2*
 tools-for-build/determine-endianness
 tools-for-build/determine-endianness.exe
 tools-for-build/grovel-headers
diff --git a/make-config.sh b/make-config.sh
index 836056715..3915c16e6 100755
--- a/make-config.sh
+++ b/make-config.sh
@@ -45,8 +45,6 @@ for dir in `cd contrib ; echo *`; do
 done
 SBCL_CONTRIB_BLOCKLIST=${SBCL_CONTRIB_BLOCKLIST:-""}
 
-echo $SBCL_CONTRIB_BLOCKLIST
-
 perform_host_lisp_check=no
 fancy=false
 some_options=false
@@ -498,8 +496,6 @@ case "$sbcl_arch" in
     x86-64) ;; *) SBCL_CONTRIB_BLOCKLIST="$SBCL_CONTRIB_BLOCKLIST sb-simd" ;;
 esac
 
-echo "SBCL_CONTRIB_BLOCKLIST=\"$SBCL_CONTRIB_BLOCKLIST\"; export SBCL_CONTRIB_BLOCKLIST" >> output/build-config
-
 echo //setting up OS-dependent information
 
 original_dir=`pwd`
@@ -658,6 +654,12 @@ case "$sbcl_arch" in
     ;;
   x86-64)
     printf ' :sb-simd-pack :sb-simd-pack-256 :avx2' >> $ltf # not mandatory
+
+    $GNUMAKE -C tools-for-build avx2
+    if tools-for-build/avx2; then
+       SBCL_CONTRIB_BLOCKLIST="$SBCL_CONTRIB_BLOCKLIST sb-simd"
+    fi
+
     case "$sbcl_os" in
     linux | darwin | *bsd)
         printf ' :immobile-space' >> $ltf
@@ -709,6 +711,8 @@ echo //finishing $ltf
 printf " %s" "`cat crossbuild-runner/backends/${sbcl_arch}/features`" >> $ltf
 echo ")) (list$WITHOUT_FEATURES)))" >> $ltf
 
+echo "SBCL_CONTRIB_BLOCKLIST=\"$SBCL_CONTRIB_BLOCKLIST\"; export SBCL_CONTRIB_BLOCKLIST" >> output/build-config
+
 # FIXME: The version system should probably be redone along these lines:
 #
 # echo //setting up version information.
diff --git a/tools-for-build/avx2.c b/tools-for-build/avx2.c
new file mode 100644
index 000000000..b16956fb2
--- /dev/null
+++ b/tools-for-build/avx2.c
@@ -0,0 +1,4 @@
+int main () {
+  __builtin_cpu_init();
+  return __builtin_cpu_supports("avx2") != 0;
+}