diff --git a/.github/workflows/tests.yml b/.github/workflows/tests.yml
index e2107406..84186393 100644
--- a/.github/workflows/tests.yml
+++ b/.github/workflows/tests.yml
@@ -13,15 +13,15 @@ jobs:
     runs-on: ${{ matrix.os }}
     strategy:
       matrix:
-        os: [ubuntu-18.04]
+        os: [ubuntu-18.04, macos-latest]
         py: [3.7, 3.8]
     defaults:
       run:
         shell: bash -l {0}
     env: 
-      DAMMIT_DB_DIR: /home/runner/databases
-      DAMMIT_CONDA_DIR: /home/runner/snakemake-envs-${{ matrix.os }}
-      DAMMIT_TESTING_TEMP_BASE_DIR: /home/runner/snakemake-envs-${{ matrix.os }}
+      DAMMIT_DB_DIR: ${{ github.workspace }}/data/databases
+      DAMMIT_CONDA_DIR: ${{ github.workspace }}/data/snakemake-envs-${{ matrix.os }}
+      DAMMIT_TESTING_TEMP_BASE_DIR: ${{ github.workspace }}/data/snakemake-envs-${{ matrix.os }}
     steps:
       - uses: actions/checkout@v2
         with:
@@ -53,11 +53,11 @@ jobs:
         uses: actions/cache@v2
         with:
           path: |
-            /home/runner/databases/Pfam-A.hmm
-            /home/runner/databases/Pfam-A.hmm.h3f
-            /home/runner/databases/Pfam-A.hmm.h3i
-            /home/runner/databases/Pfam-A.hmm.h3m
-            /home/runner/databases/Pfam-A.hmm.h3p
+            ${{ env.DAMMIT_DB_DIR }}/Pfam-A.hmm
+            ${{ env.DAMMIT_DB_DIR }}/Pfam-A.hmm.h3f
+            ${{ env.DAMMIT_DB_DIR }}/Pfam-A.hmm.h3i
+            ${{ env.DAMMIT_DB_DIR }}/Pfam-A.hmm.h3m
+            ${{ env.DAMMIT_DB_DIR }}/Pfam-A.hmm.h3p
           key: databases-${{ hashFiles('dammit/databases.yml') }}
 
       - name: setup databases
@@ -68,7 +68,7 @@ jobs:
         uses: actions/cache@v2
         with:
           path: |
-            /home/runner/snakemake-envs-${{ matrix.os }}
+            ${{ env.DAMMIT_CONDA_DIR }}
           key: ${{ matrix.os }}-snakemake-envs
 
       - name: run pytest
diff --git a/dammit/wrappers/download/wrapper.py b/dammit/wrappers/download/wrapper.py
index ed6fd2b0..46c52df1 100644
--- a/dammit/wrappers/download/wrapper.py
+++ b/dammit/wrappers/download/wrapper.py
@@ -3,6 +3,8 @@
 __email__ = "cswel@ucdavis.edu"
 __license__ = "MIT"
 
+import sys
+
 from snakemake.shell import shell
 log = snakemake.log_fmt_shell(stdout=False, stderr=True)
 
@@ -34,8 +36,11 @@
     raise ValueError('Valid filetypes are "gz", "tar.gz", and "uncompressed"')
 
 if snakemake.params.get('md5'):
-    cmd.append('&& python -c "assert \'`md5sum {output} | '
-                'awk \'{{print $1}}\'`\' == \'{snakemake.params.md5}\', '
+    if sys.platform == 'darwin':
+        md5cmd = "md5 {output} | awk '{{print $4}}'"
+    else:
+        md5cmd = "md5sum {output} | awk '{{print $1}}'"
+    cmd.append('&& python -c "assert \'`' + md5cmd + '`\' == \'{snakemake.params.md5}\', '
                 '\'MD5sum does not match\'"')
 
 cmd.append("{log}")