diff --git a/c/os_windows.c b/c/os_windows.c
index 3c87180..8d61346 100644
--- a/c/os_windows.c
+++ b/c/os_windows.c
@@ -137,3 +137,10 @@ void os_setenv(const char *name, const char *value)
         }
     }
 }
+
+value_t builtin_spawn(value_t *args, uint32_t nargs)
+{
+    (void)args;
+    (void)nargs;
+    return FL_F;
+}