diff --git a/.github/workflows/assets.yaml b/.github/workflows/assets.yaml
index 1837dd65..63c061af 100644
--- a/.github/workflows/assets.yaml
+++ b/.github/workflows/assets.yaml
@@ -32,6 +32,7 @@ jobs:
         run: |
           python -m cibuildwheel --output-dir wheelhouse
         env:
+          CIBW_ENVIRONMENT_LINUX: LIBQASM_CONAN_BUILD_PATTERNS="m4/* bison/* flex/*"
           CIBW_BEFORE_ALL_LINUX: ${{ (matrix.os == 'ubuntu-24.04-arm') && 'yum install -y java-11-openjdk' || ':' }}
       - uses: actions/upload-artifact@v4
         with:
diff --git a/setup.py b/setup.py
index a17d00df..40c29a00 100755
--- a/setup.py
+++ b/setup.py
@@ -93,6 +93,11 @@ def run(self):
         with local.cwd(root_dir):
             build_type = os.environ.get('CMAKE_BUILD_TYPE', 'Release')
             build_tests = os.environ.get('LIBQASM_BUILD_TESTS', 'False')
+            # Optional Conan build patterns to force source builds (e.g. m4/flex/bison in manylinux).
+            extra_build_patterns = [
+                pattern for pattern in os.environ.get('LIBQASM_CONAN_BUILD_PATTERNS', '').split()
+                if pattern
+            ]
 
             cmd = local['conan']['profile']['detect']['--force']
             cmd & FG
@@ -116,6 +121,8 @@ def run(self):
                 ['-b']['missing']
                 ['-tf']['']
             )
+            for pattern in extra_build_patterns:
+                cmd = cmd['-b'][pattern]
             if build_tests == 'True':
                 cmd = cmd['-c']['tools.build:skip_test=False']
             if platform.system() == 'Darwin':