diff --git a/crypto_kem/ntruhps2048509/clean/kem.c b/crypto_kem/ntruhps2048509/clean/kem.c
index 52ae34ae..09757cb2 100644
--- a/crypto_kem/ntruhps2048509/clean/kem.c
+++ b/crypto_kem/ntruhps2048509/clean/kem.c
@@ -52,7 +52,7 @@ int PQCLEAN_NTRUHPS2048509_CLEAN_crypto_kem_dec(uint8_t *k, const uint8_t *c, co
     for (i = 0; i < NTRU_CIPHERTEXTBYTES; i++) {
         cmp[i] = c[i];
     }
-    sha3_256(rm, cmp, NTRU_PRFKEYBYTES + NTRU_CIPHERTEXTBYTES);
+    sha3_256(rm, cmp, NTRU_CIPHERTEXTBYTES);
 
     PQCLEAN_NTRUHPS2048509_CLEAN_cmov(k, rm, NTRU_SHAREDKEYBYTES, (unsigned char) fail);