diff --git a/VersionedMap.cpp b/VersionedMap.cpp
index 991f82e..8e77165 100644
--- a/VersionedMap.cpp
+++ b/VersionedMap.cpp
@@ -22,7 +22,13 @@
 bool debugVerboseEnabled = true;
 #endif
 
+static_assert(std::is_standard_layout_v<weaselab::VersionedMap::MutationType>);
+static_assert(std::is_standard_layout_v<weaselab::VersionedMap::Key>);
+static_assert(std::is_standard_layout_v<weaselab::VersionedMap::Mutation>);
+static_assert(std::is_standard_layout_v<weaselab::VersionedMap::Iterator>);
 static_assert(std::bidirectional_iterator<weaselab::VersionedMap::Iterator>);
+static_assert(std::is_standard_layout_v<
+              weaselab::VersionedMap::Iterator::VersionedMutation>);
 
 void *mmapSafe(void *addr, size_t len, int prot, int flags, int fd,
                off_t offset) {
diff --git a/include/VersionedMap.h b/include/VersionedMap.h
index 00ec13c..41f03d4 100644
--- a/include/VersionedMap.h
+++ b/include/VersionedMap.h
@@ -104,7 +104,12 @@ struct VersionedMap {
     Iterator(Iterator &&) noexcept;
     Iterator &operator=(Iterator &&) noexcept;
 
-    struct VersionedMutation : Mutation {
+    struct VersionedMutation {
+      const uint8_t *param1;
+      const uint8_t *param2;
+      int param1Len;
+      int param2Len;
+      MutationType type;
       int64_t version;
     };
 
@@ -122,7 +127,7 @@ struct VersionedMap {
     Iterator operator--(int);
 
     using difference_type = ptrdiff_t;
-    using value_type = Mutation;
+    using value_type = VersionedMutation;
 
     bool operator==(const Iterator &) const;
     bool operator!=(const Iterator &) const;