diff --git a/scripts/build_runtime.py b/scripts/build_runtime.py
index 1fc9935..7dc98b0 100644
--- a/scripts/build_runtime.py
+++ b/scripts/build_runtime.py
@@ -188,13 +188,12 @@ def build_wasm3(release):
     print("Building wasm3...")
 
     os.makedirs("bin", exist_ok=True)
-    os.makedirs("bin\\obj", exist_ok=True)
+    os.makedirs("bin/obj", exist_ok=True)
 
     if platform.system() == "Windows":
         build_wasm3_lib_win(release)
     elif platform.system() == "Darwin":
-        log_error("can't yet build wasm3 on Mac")
-        exit(1)
+        build_wasm3_lib_mac(release)
     else:
         log_error(f"can't build wasm3 for unknown platform '{platform.system()}'")
         exit(1)
@@ -217,6 +216,21 @@ def build_wasm3_lib_win(release):
     ], check=True)
 
 
+def build_wasm3_lib_mac(release):
+    for f in glob.iglob("./ext/wasm3/source/*.c"):
+        name = os.path.splitext(os.path.basename(f))[0] + ".o"
+        subprocess.run([
+            "clang", "-c",
+            "-g", *(["/O2"] if release else []),
+            "-foptimize-sibling-calls", "-Wno-extern-initializer", "-Dd_m3VerboseErrorMessages",
+            "-I./ext/wasm3/source",
+            "-o", f"./bin/obj/{name}",
+            f,
+        ], check=True)
+    subprocess.run(["ar", "-rcs", "./bin/libwasm3.a", *glob.glob("./bin/obj/*.o")], check=True)
+    subprocess.run(["rm", "-rf", "./bin/obj"], check=True)
+
+
 def build_orca(release):
     print("Building Orca...")
 
@@ -225,7 +239,8 @@ def build_orca(release):
     if platform.system() == "Windows":
         build_orca_win(release)
     elif platform.system() == "Darwin":
-        raise "can't yet build Orca on Mac"
+        log_error("can't yet build Orca on Mac")
+        exit(1)
     else:
         log_error(f"can't build Orca for unknown platform '{platform.system()}'")
         exit(1)