diff --git a/Libraries/LibGfx/Font/FontData.cpp b/Libraries/LibGfx/Font/FontData.cpp
index 7865e3003ac..7053a5ed916 100644
--- a/Libraries/LibGfx/Font/FontData.cpp
+++ b/Libraries/LibGfx/Font/FontData.cpp
@@ -32,7 +32,7 @@ FontData::FontData(ByteBuffer&& byte_buffer)
 {
 }
 
-FontData::FontData(NonnullRefPtr<Core::Resource> resource)
+FontData::FontData(NonnullRefPtr<Core::Resource const> resource)
     : m_data(move(resource))
 {
 }
diff --git a/Libraries/LibGfx/Font/FontData.h b/Libraries/LibGfx/Font/FontData.h
index cb940ebd8c9..6b4cb8b45ef 100644
--- a/Libraries/LibGfx/Font/FontData.h
+++ b/Libraries/LibGfx/Font/FontData.h
@@ -19,10 +19,10 @@ public:
     ReadonlyBytes bytes() const;
 
 private:
-    FontData(ByteBuffer&& byte_buffer);
-    FontData(NonnullRefPtr<Core::Resource> resource);
+    explicit FontData(ByteBuffer&& byte_buffer);
+    explicit FontData(NonnullRefPtr<Core::Resource const> resource);
 
-    Variant<ByteBuffer, NonnullRefPtr<Core::Resource>> m_data;
+    Variant<ByteBuffer, NonnullRefPtr<Core::Resource const>> m_data;
 };
 
 }