diff --git a/quic/core/quic_connection_test.cc b/quic/core/quic_connection_test.cc
index 3c37fa7..f480f88 100644
--- a/quic/core/quic_connection_test.cc
+++ b/quic/core/quic_connection_test.cc
@@ -108,23 +108,6 @@
   }
 }
 
-// StringTaggingDecrypter ensures that the final kTagSize bytes of the message
-// match the expected value.
-class StrictTaggingDecrypter : public TaggingDecrypter {
- public:
-  explicit StrictTaggingDecrypter(uint8_t tag) : tag_(tag) {}
-  ~StrictTaggingDecrypter() override {}
-
-  // TaggingQuicDecrypter
-  uint8_t GetTag(absl::string_view /*ciphertext*/) override { return tag_; }
-
-  // Use a distinct value starting with 0xFFFFFF, which is never used by TLS.
-  uint32_t cipher_id() const override { return 0xFFFFFFF1; }
-
- private:
-  const uint8_t tag_;
-};
-
 class TestConnectionHelper : public QuicConnectionHelperInterface {
  public:
   TestConnectionHelper(MockClock* clock, MockRandom* random_generator)
diff --git a/quic/test_tools/quic_test_utils.h b/quic/test_tools/quic_test_utils.h
index efb60c5..294b7db 100644
--- a/quic/test_tools/quic_test_utils.h
+++ b/quic/test_tools/quic_test_utils.h
@@ -1865,6 +1865,23 @@
   bool CheckTag(absl::string_view ciphertext, uint8_t tag);
 };
 
+// StringTaggingDecrypter ensures that the final kTagSize bytes of the message
+// match the expected value.
+class StrictTaggingDecrypter : public TaggingDecrypter {
+ public:
+  explicit StrictTaggingDecrypter(uint8_t tag) : tag_(tag) {}
+  ~StrictTaggingDecrypter() override {}
+
+  // TaggingQuicDecrypter
+  uint8_t GetTag(absl::string_view /*ciphertext*/) override { return tag_; }
+
+  // Use a distinct value starting with 0xFFFFFF, which is never used by TLS.
+  uint32_t cipher_id() const override { return 0xFFFFFFF1; }
+
+ private:
+  const uint8_t tag_;
+};
+
 class TestPacketWriter : public QuicPacketWriter {
   struct PacketBuffer {
     QUIC_CACHELINE_ALIGNED char buffer[1500];