diff --git a/.github/deploy.yml b/.github/deploy.yml
index 046ed5d..cfcffe9 100644
--- a/.github/deploy.yml
+++ b/.github/deploy.yml
@@ -112,6 +112,10 @@ conda:
         pin_run_as_build:
             clingo: x.x
 
+        c_stdlib_version: # [osx]
+            - 10.13     # [osx and not arm64]
+            - 11.3.sdk  # [osx and arm64]
+
         # from https://github.com/phracker/MacOSX-SDKs
         CONDA_BUILD_SYSROOT:
             - /opt/MacOSX10.13.sdk # [osx and not arm64]
diff --git a/.github/workflows/conda-dev.yml b/.github/workflows/conda-dev.yml
index 9b4d140..1908ac5 100644
--- a/.github/workflows/conda-dev.yml
+++ b/.github/workflows/conda-dev.yml
@@ -16,7 +16,9 @@ jobs:
       fail-fast: false
       matrix:
         os:
+        - ubuntu-latest
         - macos-latest
+        - windows-2019
         python-version: ['3.8']
 
     steps: