Add missing ifdef for extern "C"
diff --git a/include/vulkan/vk_icd.h b/include/vulkan/vk_icd.h
index 03411e7..0f992c0 100644
--- a/include/vulkan/vk_icd.h
+++ b/include/vulkan/vk_icd.h
@@ -65,8 +65,9 @@
 
 // Prototypes for loader/ICD interface
 #if !defined(VK_NO_PROTOTYPES)
-extern "C"
-{
+#ifdef __cplusplus
+extern "C" {
+#endif
     VKAPI_ATTR VkResult VKAPI_CALL vk_icdNegotiateLoaderICDInterfaceVersion(uint32_t* pVersion);
     VKAPI_ATTR PFN_vkVoidFunction VKAPI_CALL vk_icdGetInstanceProcAddr(VkInstance instance, const char* pName);
     VKAPI_ATTR PFN_vkVoidFunction VKAPI_CALL vk_icdGetPhysicalDeviceProcAddr(VkInstance isntance, const char* pName);
@@ -74,8 +75,10 @@
     VKAPI_ATTR VkResult VKAPI_CALL vk_icdEnumerateAdapterPhysicalDevices(VkInstance instance, LUID adapterLUID,
         uint32_t* pPhysicalDeviceCount, VkPhysicalDevice* pPhysicalDevices);
 #endif
+#ifdef __cplusplus
 }
 #endif
+#endif
 
 /*
  * The ICD must reserve space for a pointer for the loader's dispatch