diff --git a/libs/freetdm/src/include/openzap.h b/libs/freetdm/src/include/openzap.h
index 5350489687..ddcb9b0133 100644
--- a/libs/freetdm/src/include/openzap.h
+++ b/libs/freetdm/src/include/openzap.h
@@ -175,6 +175,10 @@
 #include "zap_buffer.h"
 #include "zap_threadmutex.h"
 
+#ifdef __cplusplus
+extern "C" {
+#endif
+
 #ifdef __WINDOWS__
 #define zap_sleep(x) Sleep(x)
 #else
@@ -227,7 +231,7 @@
 #define zap_set_flag(obj, flag) (obj)->flags |= (flag)
 #define zap_set_flag_locked(obj, flag) assert(obj->mutex != NULL);	\
 	zap_mutex_lock(obj->mutex);										\
-	(obj)->flags |= (flag);											\
+	(obj)->flags |= (flag);          	   	                        \
 	zap_mutex_unlock(obj->mutex);
 
 #define zap_set_pflag(obj, flag) (obj)->pflags |= (flag)
@@ -317,10 +321,6 @@
 */
 #define zap_copy_flags(dest, src, flags) (dest)->flags &= ~(flags);	(dest)->flags |= ((src)->flags & (flags))
 
-#ifdef __cplusplus
-extern "C" {
-#endif
-
 typedef enum {
 	ZAP_STATE_CHANGE_FAIL,
 	ZAP_STATE_CHANGE_SUCCESS,
diff --git a/libs/freetdm/src/include/zap_types.h b/libs/freetdm/src/include/zap_types.h
index 0e0d232523..8cf2b6b30c 100644
--- a/libs/freetdm/src/include/zap_types.h
+++ b/libs/freetdm/src/include/zap_types.h
@@ -405,6 +405,17 @@ typedef enum {
 	ZAP_CHANNEL_ANSWERED = (1 << 23),
 	ZAP_CHANNEL_MUTE = (1 << 24)
 } zap_channel_flag_t;
+#if defined(__cplusplus) && defined(WIN32) 
+    // fix C2676 
+__inline__ zap_channel_flag_t operator|=(zap_channel_flag_t a, int32_t b) {
+    a = (zap_channel_flag_t)(a | b);
+    return a;
+}
+__inline__ zap_channel_flag_t operator&=(zap_channel_flag_t a, int32_t b) {
+    a = (zap_channel_flag_t)(a & b);
+    return a;
+}
+#endif
 
 typedef enum {
 	ZSM_NONE,