diff --git a/src/common/cpucores.h b/src/common/cpucores.h
index 330cd9c9..370c3cec 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, 2, &cpus, &cpus_size, NULL, 0)
+	if (sysctl(name, 2, &cpus, &cpus_size, NULL, 0) != -1
 			&& cpus_size == sizeof(cpus) && cpus > 0)
 		ret = (uint32_t)(cpus);
 #endif
diff --git a/src/common/physmem.h b/src/common/physmem.h
index 0dc77e97..74ea39e3 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, 0)) {
+	if (sysctl(name, 2, &mem.u64, &mem_ptr_size, NULL, 0) != -1) {
 		// IIRC, 64-bit "return value" is possible on some 64-bit
 		// BSD systems even with HW_PHYSMEM (instead of HW_PHYSMEM64),
 		// so support both.