diff --git a/library/bignum.c b/library/bignum.c
index 4413752633..f1e544370f 100644
--- a/library/bignum.c
+++ b/library/bignum.c
@@ -1830,7 +1830,7 @@ int mbedtls_mpi_div_mpi( mbedtls_mpi *Q, mbedtls_mpi *R, const mbedtls_mpi *A,
 
     MBEDTLS_MPI_CHK( mbedtls_mpi_grow( &Z, A->n + 2 ) );
     MBEDTLS_MPI_CHK( mbedtls_mpi_lset( &Z,  0 ) );
-    MBEDTLS_MPI_CHK( mbedtls_mpi_grow( &T1, 2 ) );
+    MBEDTLS_MPI_CHK( mbedtls_mpi_grow( &T1, A->n + 2 ) );
 
     k = mbedtls_mpi_bitlen( &Y ) % biL;
     if( k < biL - 1 )