diff --git a/stubby/Dockerfile b/stubby/Dockerfile
index 4da6818..cad3cde 100644
--- a/stubby/Dockerfile
+++ b/stubby/Dockerfile
@@ -28,11 +28,12 @@ RUN set -e -x && \
     gpg --batch --verify openssl.tar.gz.asc openssl.tar.gz && \
     tar xzf openssl.tar.gz && \
     cd "${VERSION_OPENSSL}" && \
+    /bin/sh -c 'if gcc -dM -E - </dev/null | grep -q __SIZEOF_INT128__; then export ECFLAG="enable-ec_nistp_64_gcc_128"; else export ECFLAG=""; fi' && \
     ./config \
         -Wl,-rpath=/opt/openssl/lib \
         --prefix=/opt/openssl \
         --openssldir=/opt/openssl \
-        enable-ec_nistp_64_gcc_128 \
+        $ECFLAG \
         -DOPENSSL_NO_HEARTBEATS \
         no-weak-ssl-ciphers \
         no-ssl2 \
diff --git a/unbound/Dockerfile b/unbound/Dockerfile
index 2555c04..60506ac 100644
--- a/unbound/Dockerfile
+++ b/unbound/Dockerfile
@@ -22,13 +22,14 @@ RUN set -e -x && \
     gpg --batch --verify openssl.tar.gz.asc openssl.tar.gz && \
     tar xzf openssl.tar.gz && \
     cd $VERSION_OPENSSL && \
+    /bin/sh -c 'if gcc -dM -E - </dev/null | grep -q __SIZEOF_INT128__; then export ECFLAG="enable-ec_nistp_64_gcc_128"; else export ECFLAG=""; fi' && \
     ./config \
       --prefix=/opt/openssl \
       --openssldir=/opt/openssl \
       no-weak-ssl-ciphers \
       no-ssl3 \
       no-shared \
-      enable-ec_nistp_64_gcc_128 \
+      $ECFLAG \
       -DOPENSSL_NO_HEARTBEATS \
       -fstack-protector-strong && \
     make depend && \