diff --git a/ConflictSet.cpp b/ConflictSet.cpp
index e69de29..94e25d6 100644
--- a/ConflictSet.cpp
+++ b/ConflictSet.cpp
@@ -0,0 +1,38 @@
+#include "ConflictSet.h"
+
+#include <utility>
+
+struct ConflictSet::Impl {
+  explicit Impl(int64_t oldestVersion) noexcept {}
+  void check(const ReadRange *reads, Result *results, int count) const {}
+
+  void addWrites(const WriteRange *writes, int count) {}
+
+  void setOldestVersion(int64_t oldestVersion) {}
+};
+
+void ConflictSet::check(const ReadRange *reads, Result *results,
+                        int count) const {
+  return impl->check(reads, results, count);
+}
+
+void ConflictSet::addWrites(const WriteRange *writes, int count) {
+  return impl->addWrites(writes, count);
+}
+
+void ConflictSet::setOldestVersion(int64_t oldestVersion) {
+  return impl->setOldestVersion(oldestVersion);
+}
+
+ConflictSet::ConflictSet(int64_t oldestVersion)
+    : impl(new Impl{oldestVersion}) {}
+
+ConflictSet::~ConflictSet() { delete impl; }
+
+ConflictSet::ConflictSet(ConflictSet &&other) noexcept
+    : impl(std::exchange(other.impl, nullptr)) {}
+
+ConflictSet &ConflictSet::operator=(ConflictSet &&other) noexcept {
+  impl = std::exchange(other.impl, nullptr);
+  return *this;
+}
diff --git a/ConflictSet.h b/ConflictSet.h
index b132c37..2863d0d 100644
--- a/ConflictSet.h
+++ b/ConflictSet.h
@@ -56,5 +56,6 @@ struct ConflictSet {
   ConflictSet &operator=(const ConflictSet &) = delete;
 
 private:
-  struct Impl *impl;
+  struct Impl;
+  Impl *impl;
 };
\ No newline at end of file