diff --git a/icicle/src/ntt/kernel_ntt.cu b/icicle/src/ntt/kernel_ntt.cu
index 46e97243f..6acc97528 100644
--- a/icicle/src/ntt/kernel_ntt.cu
+++ b/icicle/src/ntt/kernel_ntt.cu
@@ -702,6 +702,11 @@ namespace mxntt {
   {
     CHK_INIT_IF_RETURN();
 
+    if (log_size < 4) {
+      // TODO: fast twiddles should be used only with mixed radix ntt
+      THROW_ICICLE_ERR(IcicleError_t::InvalidArgument, "when using fast twiddles, log_size must be at least 4");
+    }
+
     S* w6_table;
     S* w12_table;
     S* w18_table;
diff --git a/icicle/src/ntt/ntt.cu b/icicle/src/ntt/ntt.cu
index 0afe4a296..0e9cbaf5c 100644
--- a/icicle/src/ntt/ntt.cu
+++ b/icicle/src/ntt/ntt.cu
@@ -469,6 +469,8 @@ namespace ntt {
       CHK_IF_RETURN(mxntt::generate_external_twiddles_generic(
         primitive_root, domain.twiddles, domain.internal_twiddles, domain.basic_twiddles, domain.max_log_size,
         ctx.stream));
+      
+      fast_twiddles_mode &= domain.max_log_size >= 4; // fast twiddles cannot be built for smaller domain
 
       if (fast_twiddles_mode) {
         // generating fast-twiddles (note that this cost 4N additional memory)