diff --git a/include/mbedtls/pkcs11.h b/include/mbedtls/pkcs11.h
index 7632929..2e88928 100644
--- a/include/mbedtls/pkcs11.h
+++ b/include/mbedtls/pkcs11.h
@@ -37,7 +37,8 @@
 
 #include <pkcs11-helper-1.0/pkcs11h-certificate.h>
 
-#if ( defined(__ARMCC_VERSION) || defined(_MSC_VER) ) && !defined(inline)
+#if ( defined(__ARMCC_VERSION) || defined(_MSC_VER) ) && \
+    !defined(inline) && !defined(__cplusplus)
 #define inline __inline
 #endif