diff --git a/library/rsa_internal.c b/library/rsa_internal.c
index f65f0df..5e35dbf 100644
--- a/library/rsa_internal.c
+++ b/library/rsa_internal.c
@@ -79,15 +79,14 @@
     mbedtls_mpi T;  /* Holds largest odd divisor of DE - 1     */
     mbedtls_mpi K;  /* Temporary holding the current candidate */
 
-    const unsigned int primes[] = { 2,
+    const unsigned char primes[] = { 2,
            3,    5,    7,   11,   13,   17,   19,   23,
           29,   31,   37,   41,   43,   47,   53,   59,
           61,   67,   71,   73,   79,   83,   89,   97,
          101,  103,  107,  109,  113,  127,  131,  137,
          139,  149,  151,  157,  163,  167,  173,  179,
          181,  191,  193,  197,  199,  211,  223,  227,
-         229,  233,  239,  241,  251,  257,  263,  269,
-         271,  277,  281,  283,  293,  307,  311,  313
+         229,  233,  239,  241,  251
     };
 
     const size_t num_primes = sizeof( primes ) / sizeof( *primes );