diff --git a/src/ieu/kmu/zknde64.sv b/src/ieu/kmu/zknde64.sv
index 51d997c12..2a6bed34a 100644
--- a/src/ieu/kmu/zknde64.sv
+++ b/src/ieu/kmu/zknde64.sv
@@ -38,12 +38,15 @@ module zknde64 import cvw::*; #(parameter cvw_t P) (
    
     if (P.ZKND_SUPPORTED) // ZKND supports aes64ds, aes64dsm, aes64im
         aes64d    aes64d(.rs1(A), .rs2(B), .finalround(ZKNSelect[2]), .aes64im(ZKNSelect[3]), .result(aes64dRes)); // decode AES
+    else assign aes64dRes = '0;
     if (P.ZKNE_SUPPORTED) begin // ZKNE supports aes64es, aes64esm
         aes64e    aes64e(.rs1(A), .rs2(B), .finalround(ZKNSelect[2]), .Sbox0Out, .SboxEIn, .result(aes64eRes));
         mux2 #(32) sboxmux(SboxEIn, SboxKIn, ZKNSelect[1], Sbox0In);
-    end else    
+    end else begin  
+        assign aes64dRes = '0;
         assign Sbox0In = SboxKIn;
-
+    end
+    
     // One S Box is always needed for aes64ks1i and is also needed for aes64e if that is supported.  Put it at the top level to allow sharing
     aessbox32 sbox(Sbox0In, Sbox0Out);                       // Substitute bytes of value obtained for tmp2 using Rijndael sbox