diff --git a/src/hotspot/os/aix/os_aix.cpp b/src/hotspot/os/aix/os_aix.cpp
index 0c1c0dbc6dc..f6312f2f882 100644
--- a/src/hotspot/os/aix/os_aix.cpp
+++ b/src/hotspot/os/aix/os_aix.cpp
@@ -278,7 +278,7 @@ julong os::Aix::available_memory() {
 
 jlong os::total_swap_space() {
   perfstat_memory_total_t memory_info;
-  if (libperfstat::perfstat_memory_total(NULL, &memory_info, sizeof(perfstat_memory_total_t), 1) == -1) {
+  if (libperfstat::perfstat_memory_total(nullptr, &memory_info, sizeof(perfstat_memory_total_t), 1) == -1) {
     return -1;
   }
   return (jlong)(memory_info.pgsp_total * 4 * K);
@@ -286,7 +286,7 @@ jlong os::total_swap_space() {
 
 jlong os::free_swap_space() {
   perfstat_memory_total_t memory_info;
-  if (libperfstat::perfstat_memory_total(NULL, &memory_info, sizeof(perfstat_memory_total_t), 1) == -1) {
+  if (libperfstat::perfstat_memory_total(nullptr, &memory_info, sizeof(perfstat_memory_total_t), 1) == -1) {
     return -1;
   }
   return (jlong)(memory_info.pgsp_free * 4 * K);
diff --git a/src/hotspot/os/bsd/os_bsd.cpp b/src/hotspot/os/bsd/os_bsd.cpp
index 0e67228de7b..86d81a59f0d 100644
--- a/src/hotspot/os/bsd/os_bsd.cpp
+++ b/src/hotspot/os/bsd/os_bsd.cpp
@@ -184,7 +184,7 @@ jlong os::total_swap_space() {
 #if defined(__APPLE__)
   struct xsw_usage vmusage;
   size_t size = sizeof(vmusage);
-  if (sysctlbyname("vm.swapusage", &vmusage, &size, NULL, 0) != 0) {
+  if (sysctlbyname("vm.swapusage", &vmusage, &size, nullptr, 0) != 0) {
     return -1;
   }
   return (jlong)vmusage.xsu_total;
@@ -197,7 +197,7 @@ jlong os::free_swap_space() {
 #if defined(__APPLE__)
   struct xsw_usage vmusage;
   size_t size = sizeof(vmusage);
-  if (sysctlbyname("vm.swapusage", &vmusage, &size, NULL, 0) != 0) {
+  if (sysctlbyname("vm.swapusage", &vmusage, &size, nullptr, 0) != 0) {
     return -1;
   }
   return (jlong)vmusage.xsu_avail;
diff --git a/test/hotspot/gtest/runtime/test_os_linux.cpp b/test/hotspot/gtest/runtime/test_os_linux.cpp
index 20a6257df04..69c3d991b2a 100644
--- a/test/hotspot/gtest/runtime/test_os_linux.cpp
+++ b/test/hotspot/gtest/runtime/test_os_linux.cpp
@@ -356,7 +356,7 @@ TEST_VM(os_linux, pretouch_thp_and_use_concurrent) {
   const bool useThp = UseTransparentHugePages;
   UseTransparentHugePages = true;
   char* const heap = os::reserve_memory(size, false, mtInternal);
-  EXPECT_NE(heap, (char*)NULL);
+  EXPECT_NE(heap, nullptr);
   EXPECT_TRUE(os::commit_memory(heap, size, false));
 
   {