diff --git a/psutil/_psutil_common.c b/psutil/_psutil_common.c
index e333c1624..5d025739f 100644
--- a/psutil/_psutil_common.c
+++ b/psutil/_psutil_common.c
@@ -70,7 +70,12 @@ psutil_pid_exists(long pid) {
 #endif
     }
 
+#if defined(PSUTIL_OSX)
+    ret = kill((pid_t)pid , 0);
+#else
     ret = kill(pid , 0);
+#endif
+
     if (ret == 0)
         return 1;
     else {
diff --git a/psutil/_psutil_osx.c b/psutil/_psutil_osx.c
index 160b02851..d1640714b 100644
--- a/psutil/_psutil_osx.c
+++ b/psutil/_psutil_osx.c
@@ -131,7 +131,6 @@ psutil_proc_name(PyObject *self, PyObject *args) {
 #else
     return Py_BuildValue("s", kp.kp_proc.p_comm);
 #endif
-
 }
 
 
@@ -895,7 +894,7 @@ static PyObject *
 psutil_disk_partitions(PyObject *self, PyObject *args) {
     int num;
     int i;
-    long len;
+    int len;
     uint64_t flags;
     char opts[400];
     struct statfs *fs = NULL;
diff --git a/psutil/arch/osx/process_info.c b/psutil/arch/osx/process_info.c
index 49382c6ca..7b650c990 100644
--- a/psutil/arch/osx/process_info.c
+++ b/psutil/arch/osx/process_info.c
@@ -110,7 +110,7 @@ PyObject *
 psutil_get_cmdline(long pid) {
     int mib[3];
     int nargs;
-    int len;
+    size_t len;
     char *procargs = NULL;
     char *arg_ptr;
     char *arg_end;
diff --git a/psutil/tests/__init__.py b/psutil/tests/__init__.py
index 6cbfb98d5..7cf820cc8 100644
--- a/psutil/tests/__init__.py
+++ b/psutil/tests/__init__.py
@@ -494,8 +494,9 @@ def create_temp_file(suffix=None):
             c_code = textwrap.dedent(
                 """
                 #include <unistd.h>
-                void main() {
+                int main() {
                     pause();
+                    return 1;
                 }
                 """)
         c_file = create_temp_file(suffix=".c")