diff --git a/include/libimp/error.h b/include/libimp/error.h
index 351ae66..6a5e67b 100644
--- a/include/libimp/error.h
+++ b/include/libimp/error.h
@@ -17,6 +17,7 @@ LIBIMP_NAMESPACE_BEG_
 
 using error_code_t = std::uint64_t;
 constexpr error_code_t error_number_limit = error_code_t(-1);
+constexpr error_code_t no_error = 0;
 
 /**
  * \brief Serves as the base class for specific error category types.
diff --git a/include/libipc/shm.h b/include/libipc/shm.h
index 9e05b36..9320654 100644
--- a/include/libipc/shm.h
+++ b/include/libipc/shm.h
@@ -21,11 +21,15 @@ using shm_t = shm_handle *;
 
 /// \brief Create a new shared memory handle with a name of the shared memory file.
 LIBIMP_EXPORT ::LIBIMP::result<shm_t> shm_open(std::string name, 
-                                                std::size_t size = 0,
-                                                mode::type = mode::create | mode::open) noexcept;
+                                               std::size_t size = 0,
+                                               mode::type = mode::create | mode::open) noexcept;
 
 /// \brief Close the shared memory handle.
-LIBIMP_EXPORT ::LIBIMP::result_code shm_close(shm_t) noexcept;
+LIBIMP_EXPORT ::LIBIMP::result<void> shm_close(shm_t) noexcept;
+
+/// \brief Gets the name of the shared memory file based on the shared memory handle.
+/// \return empty string on failure.
+LIBIMP_EXPORT std::string shm_name(shm_t) noexcept;
 
 /// \brief Gets a memory pointer based on the shared memory handle.
 /// \return nullptr on failure.
@@ -39,10 +43,6 @@ LIBIMP_EXPORT std::size_t shm_size(shm_t) noexcept;
 /// \remark [TBD]
 LIBIMP_EXPORT ::LIBIMP::result_code shm_size(shm_t, std::size_t) noexcept;
 
-/// \brief Gets the name of the shared memory file based on the shared memory handle.
-/// \return empty string on failure.
-LIBIMP_EXPORT std::string shm_name(shm_t) noexcept;
-
 /**
  * \brief The shared memory object.
  */
diff --git a/src/libipc/platform/posix/shm_impl.h b/src/libipc/platform/posix/shm_impl.h
index 2d65c47..60f302c 100644
--- a/src/libipc/platform/posix/shm_impl.h
+++ b/src/libipc/platform/posix/shm_impl.h
@@ -150,7 +150,7 @@ result<shm_t> shm_open(std::string name, std::size_t size, mode::type type) noex
 /**
  * \see https://man7.org/linux/man-pages/man2/mmap.2.html
  */
-result_code shm_close(shm_t h) noexcept {
+result<void> shm_close(shm_t h) noexcept {
   LIBIMP_LOG_();
   auto shm = valid(h);
   if (shm == nullptr) return {};
@@ -161,7 +161,7 @@ result_code shm_close(shm_t h) noexcept {
   }
   /// \brief no unlink the file.
   delete shm;
-  return posix::succ;
+  return no_error;
 }
 
 LIBIPC_NAMESPACE_END_
diff --git a/src/libipc/platform/win/mmap_impl.h b/src/libipc/platform/win/mmap_impl.h
index e1db442..9a5b78d 100644
--- a/src/libipc/platform/win/mmap_impl.h
+++ b/src/libipc/platform/win/mmap_impl.h
@@ -33,7 +33,7 @@ namespace {
  * \brief Closes an open object handle.
  * \see https://docs.microsoft.com/en-us/windows/win32/api/handleapi/nf-handleapi-closehandle
  */
-result_code mmap_close(HANDLE h) {
+result<void> mmap_close(HANDLE h) {
   LIBIMP_LOG_();
   if (h == NULL) {
     log.error("handle is null.");
@@ -44,7 +44,7 @@ result_code mmap_close(HANDLE h) {
     log.error("failed: CloseHandle(", h, "). error = ", err);
     return err;
   }
-  return ERROR_SUCCESS;
+  return no_error;
 }
 
 /**
@@ -161,7 +161,7 @@ result<SIZE_T> mmap_sizeof(LPCVOID mem) {
  * \brief Unmaps a mapped view of a file from the calling process's address space.
  * \see https://docs.microsoft.com/en-us/windows/win32/api/memoryapi/nf-memoryapi-unmapviewoffile
  */
-result_code mmap_release(HANDLE h, LPCVOID mem) {
+result<void> mmap_release(HANDLE h, LPCVOID mem) {
   LIBIMP_LOG_();
   if (h == NULL) {
     log.error("handle is null.");
diff --git a/src/libipc/platform/win/shm_impl.h b/src/libipc/platform/win/shm_impl.h
index 537b984..deec8f3 100644
--- a/src/libipc/platform/win/shm_impl.h
+++ b/src/libipc/platform/win/shm_impl.h
@@ -39,7 +39,7 @@ result<shm_t> shm_open(std::string name, std::size_t size, mode::type type) noex
   return new shm_handle{std::move(name), *sz, *mem, *h};
 }
 
-result_code shm_close(shm_t h) noexcept {
+result<void> shm_close(shm_t h) noexcept {
   LIBIMP_LOG_();
   if (h == nullptr) {
     log.error("shm handle is null.");
diff --git a/test/ipc/test_ipc_shm.cpp b/test/ipc/test_ipc_shm.cpp
index c7fcd90..4b23aaa 100644
--- a/test/ipc/test_ipc_shm.cpp
+++ b/test/ipc/test_ipc_shm.cpp
@@ -3,7 +3,7 @@
 
 #include "libipc/shm.h"
 
-TEST(shm, create_close) {
+TEST(shm, open_close) {
   EXPECT_FALSE(ipc::shm_open("hello-ipc-shm", 1024, ipc::mode::none));
 
   auto shm1 = ipc::shm_open("hello-ipc-shm", 1024, ipc::mode::create | ipc::mode::open);
@@ -77,7 +77,6 @@ TEST(shm, shared_memory) {
 }
 
 #include <libimp/detect_plat.h>
-
 #if defined(LIBIMP_OS_LINUX)
 #include <sys/socket.h>
 #include <sys/un.h>