diff --git a/doxygen/mbedtls.doxyfile b/doxygen/mbedtls.doxyfile
index 393fd41..4c95c61 100644
--- a/doxygen/mbedtls.doxyfile
+++ b/doxygen/mbedtls.doxyfile
@@ -51,4 +51,5 @@
                          "MBEDTLS_CHECK_RETURN_TYPICAL="    \
                          "MBEDTLS_CHECK_RETURN_OPTIONAL="   \
                          "MBEDTLS_PRINTF_ATTRIBUTE(a,b)="   \
+                         "__DOXYGEN__"                      \