diff --git a/configure.ac b/configure.ac
index f5b9052ff..f7bab8890 100644
--- a/configure.ac
+++ b/configure.ac
@@ -1453,7 +1453,7 @@ AC_ARG_ENABLE([lowresource],
 if test "$ENABLED_LOWRESOURCE" = "yes"
 then
     # low memory / flash flags
-    AM_CFLAGS="$AM_CFLAGS -DNO_SESSION_CACHE -DRSA_LOW_MEM -DGCM_SMALL -DCURVE25519_SMALL -DED25519_SMALL -DWOLFSSL_SMALL_CERT_VERIFY"
+    AM_CFLAGS="$AM_CFLAGS -DNO_SESSION_CACHE -DRSA_LOW_MEM -DGCM_SMALL -DCURVE25519_SMALL -DED25519_SMALL -DWOLFSSL_SMALL_CERT_VERIFY -DWOLFSSL_NO_ASYNC_IO"
 
     # low flash flags
     AM_CFLAGS="$AM_CFLAGS -DUSE_SLOW_SHA -DUSE_SLOW_SHA256 -DUSE_SLOW_SHA512"