diff --git a/crypto/fipsmodule/ml_dsa/ml_dsa_ref/poly.c b/crypto/fipsmodule/ml_dsa/ml_dsa_ref/poly.c
index 456f7b5aa3..997e7d2e0b 100644
--- a/crypto/fipsmodule/ml_dsa/ml_dsa_ref/poly.c
+++ b/crypto/fipsmodule/ml_dsa/ml_dsa_ref/poly.c
@@ -372,19 +372,19 @@ static unsigned int rej_eta(ml_dsa_params *params,
     if (params->eta == 2) {
       if(t0 < 15) {
         t0 = t0 - (205*t0 >> 10)*5;
-        a[ctr++] = 2 - t0;
+        a[ctr++] = 2 - (int32_t)t0;
       }
       if(t1 < 15 && ctr < len) {
         t1 = t1 - (205*t1 >> 10)*5;
-        a[ctr++] = 2 - t1;
+        a[ctr++] = 2 - (int32_t)t1;
       }
     }
 
     else if (params->eta == 4) {
       if(t0 < 9)
-        a[ctr++] = 4 - t0;
+        a[ctr++] = 4 - (int32_t)t0;
       if(t1 < 9 && ctr < len)
-        a[ctr++] = 4 - t1;
+        a[ctr++] = 4 - (int32_t)t1;
     }
   }
   return ctr;