diff --git a/.github/workflows/macosx-ci.yml b/.github/workflows/macosx-ci.yml
index 2270121092..eb5805e5bd 100644
--- a/.github/workflows/macosx-ci.yml
+++ b/.github/workflows/macosx-ci.yml
@@ -44,8 +44,6 @@ jobs:
         run: brew install --cask font-dejavu
       - name: Install environment helpers with homebrew
         run: brew install --force ccache
-      - name: Install LLVM with homebrew
-        run: brew install --force llvm
       - name: Install openage dependencies with homebrew
         run: brew install --force cmake python3 libepoxy freetype fontconfig harfbuzz opus opusfile qt6 libogg libpng toml11 eigen
       - name: Install nyan dependencies with homebrew
@@ -56,7 +54,7 @@ jobs:
         # numpy pulls gcc as dep? and pygments doesn't work.
         run: pip3 install --upgrade --break-system-packages cython numpy mako lz4 pillow pygments setuptools toml
       - name: Configure
-        run: ./configure --compiler="$(brew --prefix llvm)/bin/clang++" --mode=release --ccache --download-nyan
+        run: ./configure --compiler=clang --mode=release --ccache --download-nyan
       - name: Build
         run: make -j$(sysctl -n hw.logicalcpu) VERBOSE=1
       - name: Test
diff --git a/libopenage/CMakeLists.txt b/libopenage/CMakeLists.txt
index 30b7b23b01..162f513bdb 100644
--- a/libopenage/CMakeLists.txt
+++ b/libopenage/CMakeLists.txt
@@ -1,4 +1,4 @@
-# Copyright 2014-2025 the openage authors. See copying.md for legal info.
+# Copyright 2014-2026 the openage authors. See copying.md for legal info.
 
 # main C++ library definitions.
 # dependency and source file setup for the resulting library.
@@ -56,7 +56,12 @@ find_package(PNG REQUIRED)
 find_package(Opusfile REQUIRED)
 find_package(Epoxy REQUIRED)
 find_package(HarfBuzz 1.0.0 REQUIRED)
-find_package(Eigen3 3.3 REQUIRED NO_MODULE)
+# Eigen dropped strict config-version compatibility across its 3 to 5 major
+# bump, so pinning "3.3" here makes find_package reject Eigen 5 (shipped by
+# Arch and Homebrew) even though openage only uses the stable core/geometry
+# API. A version range would need cmake 3.19; our floor is 3.16, so require
+# any Eigen3 config instead.
+find_package(Eigen3 REQUIRED NO_MODULE)
 
 set(CMAKE_THREAD_PREFER_PTHREAD TRUE)
 find_package(Threads REQUIRED)