diff --git a/src/uint256.h b/src/uint256.h
index 1cc3721487..dc8887287a 100644
--- a/src/uint256.h
+++ b/src/uint256.h
@@ -22,6 +22,7 @@ class base_blob
 {
 protected:
     static constexpr int WIDTH = BITS / 8;
+    static_assert(BITS % 8 == 0, "base_blob currently only supports whole bytes.");
     std::array<uint8_t, WIDTH> m_data;
     static_assert(WIDTH == sizeof(m_data), "Sanity check");