diff --git a/include/fmt/os.h b/include/fmt/os.h
index 728a613b..c3388092 100644
--- a/include/fmt/os.h
+++ b/include/fmt/os.h
@@ -390,7 +390,7 @@ class file_buffer final : public buffer<char> {
 
  public:
   FMT_API file_buffer(cstring_view path, const ostream_params& params);
-  FMT_API file_buffer(file_buffer&& other);
+  FMT_API file_buffer(file_buffer&& other) noexcept;
   FMT_API ~file_buffer();
 
   void flush() {
diff --git a/src/os.cc b/src/os.cc
index 2ba9bc8a..81177b26 100644
--- a/src/os.cc
+++ b/src/os.cc
@@ -381,7 +381,7 @@ file_buffer::file_buffer(cstring_view path, const ostream_params& params)
   set(new char[params.buffer_size], params.buffer_size);
 }
 
-file_buffer::file_buffer(file_buffer&& other)
+file_buffer::file_buffer(file_buffer&& other) noexcept
     : buffer<char>(grow, other.data(), other.size(), other.capacity()),
       file_(std::move(other.file_)) {
   other.clear();