diff --git a/source/mijin/util/bitflags.hpp b/source/mijin/util/bitflags.hpp
index 7ffae72..dd676d0 100644
--- a/source/mijin/util/bitflags.hpp
+++ b/source/mijin/util/bitflags.hpp
@@ -68,7 +68,7 @@ struct BitFlags
         return copy;
     }
 
-    constexpr operator bool() const {
+    explicit constexpr operator bool() const {
         for (std::size_t idx = 0; idx < sizeof(TBits); ++idx) {
             if (*(std::bit_cast<const std::byte*>(asBits()) + idx) != std::byte(0)) {
                 return true;