diff --git a/ebml/EbmlElement.h b/ebml/EbmlElement.h
index 8641caa5..23d2c757 100644
--- a/ebml/EbmlElement.h
+++ b/ebml/EbmlElement.h
@@ -474,7 +474,7 @@ static inline constexpr const EbmlSemanticContext * EBML_CTX_PARENT(const EbmlSe
   return c.Parent();
 }
 
-static inline const EbmlSemantic & EBML_CTX_IDX(const EbmlSemanticContext & c, std::size_t i)
+static inline constexpr const EbmlSemantic & EBML_CTX_IDX(const EbmlSemanticContext & c, std::size_t i)
 {
   return c.GetSemantic(i);
 }