diff --git a/vulkan/libvulkan/debug_report.h b/vulkan/libvulkan/debug_report.h
index be9b645..3d8bd50 100644
--- a/vulkan/libvulkan/debug_report.h
+++ b/vulkan/libvulkan/debug_report.h
@@ -85,9 +85,9 @@
 
 class DebugReportLogger {
    public:
-    DebugReportLogger(const VkInstanceCreateInfo& info)
+    explicit DebugReportLogger(const VkInstanceCreateInfo& info)
         : instance_pnext_(info.pNext), callbacks_(nullptr) {}
-    DebugReportLogger(const DebugReportCallbackList& callbacks)
+    explicit DebugReportLogger(const DebugReportCallbackList& callbacks)
         : instance_pnext_(nullptr), callbacks_(&callbacks) {}
 
     void Message(VkDebugReportFlagsEXT flags,
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(),
diff --git a/vulkan/libvulkan/layers_extensions.h b/vulkan/libvulkan/layers_extensions.h
index 79fe59d..07ac1a3 100644
--- a/vulkan/libvulkan/layers_extensions.h
+++ b/vulkan/libvulkan/layers_extensions.h
@@ -26,7 +26,7 @@
 
 class LayerRef {
    public:
-    LayerRef(const Layer* layer);
+    explicit LayerRef(const Layer* layer);
     LayerRef(LayerRef&& other);
     ~LayerRef();
     LayerRef(const LayerRef&) = delete;