diff --git a/libraries/libstratosphere/include/stratosphere/fs/fsa/fs_ifile.hpp b/libraries/libstratosphere/include/stratosphere/fs/fsa/fs_ifile.hpp
index 9ca61db0d..687751800 100644
--- a/libraries/libstratosphere/include/stratosphere/fs/fsa/fs_ifile.hpp
+++ b/libraries/libstratosphere/include/stratosphere/fs/fsa/fs_ifile.hpp
@@ -36,12 +36,10 @@ namespace ams::fs::fsa {
                 }
 
                 /* Check that the read is valid. */
-                R_UNLESS(buffer != nullptr,                        fs::ResultNullptrArgument());
-                R_UNLESS(offset >= 0,                              fs::ResultOutOfRange());
-                R_UNLESS(util::IsIntValueRepresentable<s64>(size), fs::ResultOutOfRange());
-
-                const s64 signed_size = static_cast<s64>(size);
-                R_UNLESS((std::numeric_limits<s64>::max() - offset) >= signed_size, fs::ResultOutOfRange());
+                R_UNLESS(buffer != nullptr,                              fs::ResultNullptrArgument());
+                R_UNLESS(offset >= 0,                                    fs::ResultOutOfRange());
+                R_UNLESS(util::IsIntValueRepresentable<s64>(size),       fs::ResultOutOfRange());
+                R_UNLESS(util::CanAddWithoutOverflow<s64>(offset, size), fs::ResultOutOfRange());
 
                 /* Do the read. */
                 R_RETURN(this->DoRead(out, offset, buffer, size, option));
@@ -68,12 +66,10 @@ namespace ams::fs::fsa {
                 }
 
                 /* Check the write is valid. */
-                R_UNLESS(buffer != nullptr,                        fs::ResultNullptrArgument());
-                R_UNLESS(offset >= 0,                              fs::ResultOutOfRange());
-                R_UNLESS(util::IsIntValueRepresentable<s64>(size), fs::ResultOutOfRange());
-
-                const s64 signed_size = static_cast<s64>(size);
-                R_UNLESS((std::numeric_limits<s64>::max() - offset) >= signed_size, fs::ResultOutOfRange());
+                R_UNLESS(buffer != nullptr,                              fs::ResultNullptrArgument());
+                R_UNLESS(offset >= 0,                                    fs::ResultOutOfRange());
+                R_UNLESS(util::IsIntValueRepresentable<s64>(size),       fs::ResultOutOfRange());
+                R_UNLESS(util::CanAddWithoutOverflow<s64>(offset, size), fs::ResultOutOfRange());
 
                 R_RETURN(this->DoWrite(offset, buffer, size, option));
             }
diff --git a/libraries/libstratosphere/source/time/impl/util/time_impl_util_api.cpp b/libraries/libstratosphere/source/time/impl/util/time_impl_util_api.cpp
index 8cb8f961e..3226db2b4 100644
--- a/libraries/libstratosphere/source/time/impl/util/time_impl_util_api.cpp
+++ b/libraries/libstratosphere/source/time/impl/util/time_impl_util_api.cpp
@@ -157,11 +157,7 @@ namespace ams::time::impl::util {
         R_UNLESS(out != nullptr,                 time::ResultInvalidPointer());
         R_UNLESS(from.source_id == to.source_id, time::ResultNotComparable());
 
-        const bool no_overflow = (from.value >= 0 ? (to.value >= std::numeric_limits<s64>::min() + from.value)
-                                                  : (to.value <= std::numeric_limits<s64>::max() + from.value));
-        R_UNLESS(no_overflow, time::ResultOverflowed());
-
-        *out = to.value - from.value;
+        R_UNLESS(ams::util::TrySubtractWithoutOverflow(out, to.value, from.value), time::ResultOverflowed());
         return ResultSuccess();
     }
 
diff --git a/stratosphere/ams_mitm/source/sysupdater/sysupdater_fs_utils.cpp b/stratosphere/ams_mitm/source/sysupdater/sysupdater_fs_utils.cpp
index 722c895ee..c78e43add 100644
--- a/stratosphere/ams_mitm/source/sysupdater/sysupdater_fs_utils.cpp
+++ b/stratosphere/ams_mitm/source/sysupdater/sysupdater_fs_utils.cpp
@@ -123,7 +123,7 @@ namespace ams::mitm::sysupdater {
 
             /* Open the file storage. */
             std::shared_ptr<ams::fs::FileStorageBasedFileSystem> file_storage = fssystem::AllocateShared<ams::fs::FileStorageBasedFileSystem>();
-            R_UNLESS(file_storage != nullptr, fs::ResultAllocationMemoryFailedInFileSystemProxyCoreImplD());
+            R_UNLESS(file_storage != nullptr, fs::ResultAllocationMemoryFailedInNcaFileSystemServiceImplA());
             R_TRY(file_storage->Initialize(std::move(base_fs), nsp_path, ams::fs::OpenMode_Read));
 
             /* Create a partition fs. */
@@ -138,7 +138,7 @@ namespace ams::mitm::sysupdater {
         Result ParseNca(const char **path, std::shared_ptr<fssystem::NcaReader> *out, std::shared_ptr<ams::fs::fsa::IFileSystem> base_fs) {
             /* Open the file storage. */
             std::shared_ptr<ams::fs::FileStorageBasedFileSystem> file_storage = fssystem::AllocateShared<ams::fs::FileStorageBasedFileSystem>();
-            R_UNLESS(file_storage != nullptr, fs::ResultAllocationMemoryFailedInFileSystemProxyCoreImplE());
+            R_UNLESS(file_storage != nullptr, fs::ResultAllocationMemoryFailedInNcaFileSystemServiceImplB());
 
             /* Get the nca path. */
             ams::fs::Path nca_path;