diff --git a/m4/lc_cpucores.m4 b/m4/lc_cpucores.m4
index 2fae953a..52f7c985 100644
--- a/m4/lc_cpucores.m4
+++ b/m4/lc_cpucores.m4
@@ -43,7 +43,7 @@ main(void)
 	int name[2] = { CTL_HW, HW_NCPU };
 	int cpus;
 	size_t cpus_size = sizeof(cpus);
-	sysctl(name, 2, &cpus, &cpus_size, NULL, NULL);
+	sysctl(name, 2, &cpus, &cpus_size, NULL, 0);
 	return 0;
 }
 ]])], [
diff --git a/m4/lc_physmem.m4 b/m4/lc_physmem.m4
index 78be1362..5d9581e1 100644
--- a/m4/lc_physmem.m4
+++ b/m4/lc_physmem.m4
@@ -45,7 +45,7 @@ main(void)
 	int name[2] = { CTL_HW, HW_PHYSMEM };
 	unsigned long mem;
 	size_t mem_ptr_size = sizeof(mem);
-	sysctl(name, 2, &mem, &mem_ptr_size, NULL, NULL);
+	sysctl(name, 2, &mem, &mem_ptr_size, NULL, 0);
 	return 0;
 }
 ]])], [
diff --git a/src/common/cpucores.h b/src/common/cpucores.h
index 704d8a26..330cd9c9 100644
--- a/src/common/cpucores.h
+++ b/src/common/cpucores.h
@@ -40,7 +40,7 @@ cpucores(void)
 	int name[2] = { CTL_HW, HW_NCPU };
 	int cpus;
 	size_t cpus_size = sizeof(cpus);
-	if (!sysctl(name, &cpus, &cpus_size, NULL, NULL)
+	if (!sysctl(name, 2, &cpus, &cpus_size, NULL, 0)
 			&& cpus_size == sizeof(cpus) && cpus > 0)
 		ret = (uint32_t)(cpus);
 #endif
diff --git a/src/common/physmem.h b/src/common/physmem.h
index 63482c6c..0dc77e97 100644
--- a/src/common/physmem.h
+++ b/src/common/physmem.h
@@ -104,7 +104,7 @@ physmem(void)
 		uint64_t u64;
 	} mem;
 	size_t mem_ptr_size = sizeof(mem.u64);
-	if (!sysctl(name, 2, &mem.u64, &mem_ptr_size, NULL, NULL)) {
+	if (!sysctl(name, 2, &mem.u64, &mem_ptr_size, NULL, 0)) {
 		// IIRC, 64-bit "return value" is possible on some 64-bit
 		// BSD systems even with HW_PHYSMEM (instead of HW_PHYSMEM64),
 		// so support both.