diff --git a/src/GraphingImpl/Mocks/Bitmap.h b/src/GraphingImpl/Mocks/Bitmap.h
index eaf3973d..c4e1a2a0 100644
--- a/src/GraphingImpl/Mocks/Bitmap.h
+++ b/src/GraphingImpl/Mocks/Bitmap.h
@@ -9,7 +9,7 @@ namespace MockGraphingImpl
 {
     class Bitmap : public Graphing::IBitmap
     {
-        virtual const std::vector<BYTE> GetData() const
+        virtual std::vector<BYTE> GetData() const
         {
             return std::vector<BYTE>();
         }
diff --git a/src/GraphingImpl/Mocks/Graph.h b/src/GraphingImpl/Mocks/Graph.h
index 8624d92d..3678074c 100644
--- a/src/GraphingImpl/Mocks/Graph.h
+++ b/src/GraphingImpl/Mocks/Graph.h
@@ -29,7 +29,7 @@ namespace MockGraphingImpl
             return std::nullopt;
         }
 
-        HRESULT GetInitializationError()
+        HRESULT GetInitializationError() const
         {
             return S_OK;
         }
diff --git a/src/GraphingInterfaces/IBitmap.h b/src/GraphingInterfaces/IBitmap.h
index d9285a50..7ce7a7ca 100644
--- a/src/GraphingInterfaces/IBitmap.h
+++ b/src/GraphingInterfaces/IBitmap.h
@@ -9,6 +9,6 @@ namespace Graphing
 {
     struct IBitmap
     {
-        virtual const std::vector<BYTE> GetData() const = 0;
+        virtual std::vector<BYTE> GetData() const = 0;
     };
 }
diff --git a/src/GraphingInterfaces/IGraph.h b/src/GraphingInterfaces/IGraph.h
index c19c7d80..4a2e134d 100644
--- a/src/GraphingInterfaces/IGraph.h
+++ b/src/GraphingInterfaces/IGraph.h
@@ -18,7 +18,7 @@ namespace Graphing
 
         virtual std::optional<std::vector<std::shared_ptr<IEquation>>> TryInitialize(const IExpression* graphingExp = nullptr) = 0;
 
-        virtual HRESULT GetInitializationError() = 0;
+        virtual HRESULT GetInitializationError() const = 0;
 
         virtual IGraphingOptions& GetOptions() = 0;