diff --git a/macOS/build.sh b/macOS/build.sh
index 89eda987877bc104121a4dba597d4cc57770811b..df4a9a21a8d2998d45a157da1950128c41dbf987 100755
--- a/macOS/build.sh
+++ b/macOS/build.sh
@@ -40,6 +40,11 @@ else
 fi
 MATLAB_PATH=/Applications/"$PKG_ARCH"/MATLAB_R2024a.app
 
+# Workaround for bug in Xcode 15.3 which does not include m4
+# See https://github.com/Homebrew/homebrew-core/issues/165388
+# and https://trac.macports.org/ticket/69639
+path_prepend PATH "$BREWDIR"/opt/m4/bin
+
 # Append texbin to PATH to access latexmk and friends
 path_prepend PATH /Library/TeX/texbin
 
diff --git a/preprocessor b/preprocessor
index 2b4f28c7a235fe8e05cd0ec4ecf5ca0d54a88ce6..31080eed6ce6c623863850d4e2da5f8317f2b5d0 160000
--- a/preprocessor
+++ b/preprocessor
@@ -1 +1 @@
-Subproject commit 2b4f28c7a235fe8e05cd0ec4ecf5ca0d54a88ce6
+Subproject commit 31080eed6ce6c623863850d4e2da5f8317f2b5d0