diff --git a/library/x509_crt.c b/library/x509_crt.c
index 92ab38d..c2c9064 100644
--- a/library/x509_crt.c
+++ b/library/x509_crt.c
@@ -1169,13 +1169,13 @@
     if( dir == NULL )
         return( MBEDTLS_ERR_X509_FILE_IO_ERROR );
 
-#if defined(MBEDTLS_THREADING_PTHREAD)
+#if defined(MBEDTLS_THREADING_C)
     if( ( ret = mbedtls_mutex_lock( &mbedtls_threading_readdir_mutex ) ) != 0 )
     {
         closedir( dir );
         return( ret );
     }
-#endif
+#endif /* MBEDTLS_THREADING_C */
 
     while( ( entry = readdir( dir ) ) != NULL )
     {
@@ -1202,10 +1202,10 @@
     closedir( dir );
 
 cleanup:
-#if defined(MBEDTLS_THREADING_PTHREAD)
+#if defined(MBEDTLS_THREADING_C)
     if( mbedtls_mutex_unlock( &mbedtls_threading_readdir_mutex ) != 0 )
         ret = MBEDTLS_ERR_THREADING_MUTEX_ERROR;
-#endif
+#endif /* MBEDTLS_THREADING_C */
 
 #endif /* _WIN32 */