diff --git a/include/mbedtls/rsa.h b/include/mbedtls/rsa.h
index d711e05..94e0b28 100644
--- a/include/mbedtls/rsa.h
+++ b/include/mbedtls/rsa.h
@@ -364,11 +364,11 @@
  * \return         0 if successful, non-zero error code on failure.
  */
 int mbedtls_rsa_import_raw( mbedtls_rsa_context *ctx,
-                            unsigned char *N, size_t N_len,
-                            unsigned char *P, size_t P_len,
-                            unsigned char *Q, size_t Q_len,
-                            unsigned char *D, size_t D_len,
-                            unsigned char *E, size_t E_len );
+                            unsigned char const *N, size_t N_len,
+                            unsigned char const *P, size_t P_len,
+                            unsigned char const *Q, size_t Q_len,
+                            unsigned char const *D, size_t D_len,
+                            unsigned char const *E, size_t E_len );
 
 /**
  * \brief          Attempt to complete an RSA context from