diff --git a/api/include/opentelemetry/trace/span_id.h b/api/include/opentelemetry/trace/span_id.h
index e282a2021a..fe2953a0b3 100644
--- a/api/include/opentelemetry/trace/span_id.h
+++ b/api/include/opentelemetry/trace/span_id.h
@@ -61,7 +61,8 @@ class SpanId final
   bool IsValid() const noexcept
   {
     static_assert(kSize == 8, "update is needed if kSize is not 8");
-    return *reinterpret_cast<const uint64_t *>(&rep_) != 0ull;
+    static constexpr uint8_t kEmptyRep[kSize] = {0};
+    return memcmp(rep_, kEmptyRep, kSize) != 0;
   }
 
   // Copies the opaque SpanId data to dest.