diff --git a/include/mbedtls/rsa.h b/include/mbedtls/rsa.h
index df66524..e5e172f 100644
--- a/include/mbedtls/rsa.h
+++ b/include/mbedtls/rsa.h
@@ -869,6 +869,7 @@
                                       const unsigned char *hash,
                                       unsigned char *sig);
 
+#if defined(MBEDTLS_PKCS1_V21)
 /**
  * \brief          This function performs a PKCS#1 v2.1 PSS signature
  *                 operation (RSASSA-PSS-SIGN).
@@ -969,6 +970,7 @@
                                 unsigned int hashlen,
                                 const unsigned char *hash,
                                 unsigned char *sig);
+#endif /* MBEDTLS_PKCS1_V21 */
 
 /**
  * \brief          This function performs a public RSA operation and checks