diff --git a/ChangeLog b/ChangeLog
index 491b18b..84ca368 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -5,6 +5,9 @@
 Bugfix
    * Add a check if iv_len is zero, and return an error if it is zero. reported
      by roberto. #716
+   * Replace preproccessor condition from #if defined(MBEDTLS_THREADING_PTHREAD)
+     to #if defined(MBEDTLS_THREADING_C) as the library cannot assume they will
+     always be implemented by pthread support. Fix for #696
 
 Changes
    * Removed mutexes from ECP hardware accelerator code. Now all hardware
diff --git a/library/x509_crt.c b/library/x509_crt.c
index d86857d..915a7f6 100644
--- a/library/x509_crt.c
+++ b/library/x509_crt.c
@@ -1171,13 +1171,13 @@
     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 )
     {
@@ -1210,10 +1210,10 @@
 cleanup:
     closedir( dir );
 
-#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 */