diff --git a/.github/workflows/build.yml b/.github/workflows/build.yml
index 0bb9ee0..67712b9 100644
--- a/.github/workflows/build.yml
+++ b/.github/workflows/build.yml
@@ -242,7 +242,7 @@ jobs:
           gh release upload ${{ github.event.release.tag_name }} rapidsnark-linux-arm64-${{ github.ref_name }}.zip
 
   build-apple-arm64:
-    runs-on: macos-14
+    runs-on: macos-15
     steps:
       - uses: actions/checkout@v4
         with:
diff --git a/build_gmp.sh b/build_gmp.sh
index a11ab98..70bd656 100755
--- a/build_gmp.sh
+++ b/build_gmp.sh
@@ -322,6 +322,7 @@ build_macos_arch()
   cd "$BUILD_DIR"
   ../configure --prefix="${PACKAGE_DIR}" \
          CC="$(xcrun --sdk macosx --find clang)" \
+         CPP_FOR_BUILD="$(xcrun --sdk macosx --find clang) -E" \
          CFLAGS="-O3 -isysroot $(xcrun --sdk macosx --show-sdk-path) ${ARCH_FLAGS} -fvisibility=hidden -mmacos-version-min=14.0" \
          LDFLAGS="" \
          --host "${ARCH}-apple-darwin" --disable-assembly --enable-static --disable-shared --with-pic &&
diff --git a/src/prover.cpp b/src/prover.cpp
index 6f79147..60b868d 100644
--- a/src/prover.cpp
+++ b/src/prover.cpp
@@ -364,6 +364,9 @@ groth16_prover_prove(
                                   stringPublic.length(), public_size,
                                   "Required");
 
+        *proof_size = stringProof.length();
+        *public_size = stringPublic.length();
+
         std::strncpy(proof_buffer, stringProof.c_str(), *proof_size);
         std::strncpy(public_buffer, stringPublic.c_str(), *public_size);