diff --git a/.github/workflows/verify-pull-request.yml b/.github/workflows/verify-pull-request.yml
index da4ea56..ccaedad 100644
--- a/.github/workflows/verify-pull-request.yml
+++ b/.github/workflows/verify-pull-request.yml
@@ -8,6 +8,7 @@ jobs:
     strategy:
       matrix:
         cpp-compiler: ["clang", "gcc"]
+        options: ["-c opt", ""]
     steps:
       - uses: actions/checkout@v4
       - uses: bazel-contrib/setup-bazel@0.8.5
@@ -16,7 +17,7 @@ jobs:
           disk-cache: "verify-pr:run-bazel-tests:${{ matrix.cpp-compiler }}"
           repository-cache: true
       - run: echo "CC=${{ matrix.cpp-compiler }}" >> $GITHUB_ENV
-      - run: bazel test ...
+      - run: bazel test ${{ matrix.options }} ...
   check-formatting:
     name: "Check Python formatting"
     runs-on: ubuntu-latest
diff --git a/runtime/cpp/emboss_defines.h b/runtime/cpp/emboss_defines.h
index e247d00..24b5af0 100644
--- a/runtime/cpp/emboss_defines.h
+++ b/runtime/cpp/emboss_defines.h
@@ -161,6 +161,27 @@
                   static_cast</**/ ::std::uintptr_t>((offset)))
 #endif  // !defined(EMBOSS_CHECK_POINTER_ALIGNMENT)
 
+// https://gcc.gnu.org/bugzilla/show_bug.cgi?id=115033
+//
+// This affects Emboss: without the fix in the appropriate bug, we get a
+// miscompilation for some Emboss code, including some unit tests.
+//
+// It is not known whether the workaround on the Emboss side is complete, so
+// the recommendation is to move to a version of GCC that is not affected.
+// However, changing toolchains can be difficult, so we do provide a
+// workaround.
+#if !defined(EMBOSS_GCC_BUG_115033)
+#if defined(__clang__)
+#define EMBOSS_GCC_BUG_115033 0
+#elif __GNUC__ >= 12 && __GNUC__ <= 13
+#define EMBOSS_GCC_BUG_115033 1
+#elif __GNUC__ == 14 && __GNUC_MINOR__ < 2
+#define EMBOSS_GCC_BUG_115033 1
+#else
+#define EMBOSS_GCC_BUG_115033 0
+#endif
+#endif
+
 // EMBOSS_NO_OPTIMIZATIONS is used to turn off all system-specific
 // optimizations.  This is mostly intended for testing, but could be used if
 // optimizations are causing problems.
diff --git a/runtime/cpp/emboss_memory_util.h b/runtime/cpp/emboss_memory_util.h
index 09be2f1..fca71c9 100644
--- a/runtime/cpp/emboss_memory_util.h
+++ b/runtime/cpp/emboss_memory_util.h
@@ -412,8 +412,28 @@ class ContiguousBuffer final {
   explicit ContiguousBuffer(::std::nullptr_t) : bytes_{nullptr}, size_{0} {}
 
   // Implicitly construct or assign a ContiguousBuffer from a ContiguousBuffer.
+#if !EMBOSS_GCC_BUG_115033
   ContiguousBuffer(const ContiguousBuffer &other) = default;
-  ContiguousBuffer& operator=(const ContiguousBuffer& other) = default;
+  ContiguousBuffer &operator=(const ContiguousBuffer &other) = default;
+#else
+  // See https://gcc.gnu.org/bugzilla/show_bug.cgi?id=115033 for details on the
+  // bug (determined by bisecting GCC).
+  // https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114207 may also be relevant.
+  //
+  // A minimized example is available at https://godbolt.org/z/489z7z135
+  //
+  // It is not entirely clear how these definitions work around the GCC bug,
+  // but they appear to.  One notable difference (and also the main reason that
+  // we only use these definitions for affected versions of GCC) is that they
+  // change the ABI of ContiguousBuffer, at least in the minimized case.
+  ContiguousBuffer(const ContiguousBuffer &other)
+      : bytes_{other.bytes_}, size_{other.size_} {}
+  ContiguousBuffer &operator=(const ContiguousBuffer &other) {
+    bytes_ = other.bytes_;
+    size_ = other.size_;
+    return *this;
+  }
+#endif
 
   // Explicitly construct a ContiguousBuffers from another, compatible
   // ContiguousBuffer.  A compatible ContiguousBuffer has an