diff --git a/filament/backend/src/metal/MetalHandles.mm b/filament/backend/src/metal/MetalHandles.mm
index b56c8813ca..a16d149135 100644
--- a/filament/backend/src/metal/MetalHandles.mm
+++ b/filament/backend/src/metal/MetalHandles.mm
@@ -22,6 +22,8 @@
 
 #include <filament/SwapChain.h>
 
+#include <backend/DriverEnums.h>
+
 #include "private/backend/BackendUtils.h"
 
 #include <utils/Panic.h>
diff --git a/filament/backend/src/vulkan/VulkanHandles.h b/filament/backend/src/vulkan/VulkanHandles.h
index 8835d2b7b0..c6dbb71042 100644
--- a/filament/backend/src/vulkan/VulkanHandles.h
+++ b/filament/backend/src/vulkan/VulkanHandles.h
@@ -117,18 +117,18 @@ struct VulkanRenderPrimitive : public HwRenderPrimitive {
 };
 
 struct VulkanFence : public HwFence {
-    VulkanFence(const VulkanCommandBuffer& commands) : fence(commands.fence) {}
+    explicit VulkanFence(const VulkanCommandBuffer& commands) : fence(commands.fence) {}
     std::shared_ptr<VulkanCmdFence> fence;
 };
 
 struct VulkanSync : public HwSync {
-    VulkanSync() {}
-    VulkanSync(const VulkanCommandBuffer& commands) : fence(commands.fence) {}
+    VulkanSync() = default;
+    explicit VulkanSync(const VulkanCommandBuffer& commands) : fence(commands.fence) {}
     std::shared_ptr<VulkanCmdFence> fence;
 };
 
 struct VulkanTimerQuery : public HwTimerQuery {
-    VulkanTimerQuery(VulkanContext& context);
+    explicit VulkanTimerQuery(VulkanContext& context);
     ~VulkanTimerQuery();
     uint32_t startingQueryIndex;
     uint32_t stoppingQueryIndex;