diff --git a/vulkan/libvulkan/layers_extensions.cpp b/vulkan/libvulkan/layers_extensions.cpp
index 08038b7..93e83af 100644
--- a/vulkan/libvulkan/layers_extensions.cpp
+++ b/vulkan/libvulkan/layers_extensions.cpp
@@ -424,7 +424,7 @@
     return GetLayerRef(g_device_layers, name);
 }
 
-LayerRef::LayerRef(Layer* layer) : layer_(layer) {}
+LayerRef::LayerRef(const Layer* layer) : layer_(layer) {}
 
 LayerRef::~LayerRef() {
     if (layer_) {
@@ -437,7 +437,7 @@
     return layer_->properties.layerName;
 }
 
-uint32_t LayerRef::GetSpecVersion() {
+uint32_t LayerRef::GetSpecVersion() const {
     return layer_->properties.specVersion;
 }
 
diff --git a/vulkan/libvulkan/layers_extensions.h b/vulkan/libvulkan/layers_extensions.h
index 7e7bfd3..64fe5ef 100644
--- a/vulkan/libvulkan/layers_extensions.h
+++ b/vulkan/libvulkan/layers_extensions.h
@@ -25,14 +25,14 @@
 struct Layer;
 class LayerRef {
    public:
-    LayerRef(Layer* layer);
+    LayerRef(const Layer* layer);
     LayerRef(LayerRef&& other);
     ~LayerRef();
     LayerRef(const LayerRef&) = delete;
     LayerRef& operator=(const LayerRef&) = delete;
 
     const char* GetName() const;
-    uint32_t GetSpecVersion();
+    uint32_t GetSpecVersion() const;
 
     // provides bool-like behavior
     operator const Layer*() const { return layer_; }
@@ -43,7 +43,7 @@
     bool SupportsExtension(const char* name) const;
 
    private:
-    Layer* layer_;
+    const Layer* layer_;
 };
 
 void DiscoverLayers();