diff --git a/library/bignum.c b/library/bignum.c
index 7661dd3aea..9c686ad275 100644
--- a/library/bignum.c
+++ b/library/bignum.c
@@ -1706,7 +1706,7 @@ int mbedtls_mpi_exp_mod(mbedtls_mpi *X, const mbedtls_mpi *A,
      */
     const size_t x_index = 0;
     mbedtls_mpi_init(&W[x_index]);
-    MBEDTLS_MPI_CHK(mbedtls_mpi_copy(&W[x_index], X));
+    mbedtls_mpi_copy(&W[x_index], X);
 
     j = N->n + 1;
     /* All W[i] and X must have at least N->n limbs for the mpi_montmul()