diff --git a/vulkan/libvulkan/driver.h b/vulkan/libvulkan/driver.h
index a02ebd7..a1612c7 100644
--- a/vulkan/libvulkan/driver.h
+++ b/vulkan/libvulkan/driver.h
@@ -61,7 +61,7 @@
 VK_DEFINE_HANDLE(DeviceDispatchable)
 
 struct InstanceData {
-    InstanceData(const VkAllocationCallbacks& alloc)
+    explicit InstanceData(const VkAllocationCallbacks& alloc)
         : opaque_api_data(),
           allocator(alloc),
           driver(),