diff --git a/Source/Core/DiscIO/VolumeVerifier.cpp b/Source/Core/DiscIO/VolumeVerifier.cpp
index e7d325d918..9389ae0fbf 100644
--- a/Source/Core/DiscIO/VolumeVerifier.cpp
+++ b/Source/Core/DiscIO/VolumeVerifier.cpp
@@ -446,7 +446,7 @@ void VolumeVerifier::CheckDiscSize()
   }
 }
 
-u64 VolumeVerifier::GetBiggestUsedOffset()
+u64 VolumeVerifier::GetBiggestUsedOffset() const
 {
   std::vector<Partition> partitions = m_volume.GetPartitions();
   if (partitions.empty())
diff --git a/Source/Core/DiscIO/VolumeVerifier.h b/Source/Core/DiscIO/VolumeVerifier.h
index f302891431..31a4e591d9 100644
--- a/Source/Core/DiscIO/VolumeVerifier.h
+++ b/Source/Core/DiscIO/VolumeVerifier.h
@@ -99,7 +99,7 @@ private:
   bool ShouldHaveMasterpiecePartitions() const;
   bool ShouldBeDualLayer() const;
   void CheckDiscSize();
-  u64 GetBiggestUsedOffset();
+  u64 GetBiggestUsedOffset() const;
   u64 GetBiggestUsedOffset(const FileInfo& file_info) const;
   void CheckMisc();
   void SetUpHashing();