diff --git a/lib/std/io/os/fileinfo.c3 b/lib/std/io/os/fileinfo.c3
index ebddfb1e8..afde1aab9 100644
--- a/lib/std/io/os/fileinfo.c3
+++ b/lib/std/io/os/fileinfo.c3
@@ -95,7 +95,7 @@ fn bool native_is_file(String path)
 		$case env::DARWIN:
 		$case env::LINUX:
 			Stat stat;
-			return @ok(native_stat(&stat, path)) && stat.st_mode & libc::S_IFREG;
+			return @ok(native_stat(&stat, path)) && libc_S_ISTYPE(stat.st_mode, libc::S_IFREG);
 		$default:
 			File! f = file::open(path, "r");
 			defer (void)f.close();
@@ -107,7 +107,7 @@ fn bool native_is_dir(String path)
 {
 	$if env::DARWIN || env::LINUX:
 		Stat stat;
-		return @ok(native_stat(&stat, path)) && stat.st_mode & libc::S_IFDIR;
+		return @ok(native_stat(&stat, path)) && libc_S_ISTYPE(stat.st_mode, libc::S_IFDIR);
 	$else
 		return native_file_or_dir_exists(path) && !native_is_file(path);
 	$endif
diff --git a/lib/std/libc/libc.c3 b/lib/std/libc/libc.c3
index bf7c65eba..7f9803394 100644
--- a/lib/std/libc/libc.c3
+++ b/lib/std/libc/libc.c3
@@ -360,6 +360,7 @@ const int EOF = -1;
 const int FOPEN_MAX = 20;
 const int FILENAME_MAX = 1024;
 
+macro bool libc_S_ISTYPE(value, mask) @builtin => (value & S_IFMT) == mask;
 const S_IFMT   = 0o170000; // type of file mask
 const S_IFIFO  = 0o010000; // named pipe (fifo)
 const S_IFCHR  = 0o020000; // character special
diff --git a/test/unit/stdlib/io/fileinfo.c3 b/test/unit/stdlib/io/fileinfo.c3
new file mode 100644
index 000000000..b682f6ab6
--- /dev/null
+++ b/test/unit/stdlib/io/fileinfo.c3
@@ -0,0 +1,16 @@
+module std::io::fileinfo @test;
+import std::io::os;
+
+fn void test_native_is_file() @if(env::LINUX || env::DARWIN)
+{
+	assert(!os::native_is_file("/dev/loop0"));
+	assert(!os::native_is_file("/dev/null"));
+}
+
+fn void test_native_is_dir() @if(env::LINUX || env::DARWIN)
+{
+	assert(os::native_is_dir("/"));
+	assert(!os::native_is_file("/"));
+	assert(!os::native_is_dir("/dev/loop0"));
+	assert(!os::native_is_dir("/dev/null"));
+}
\ No newline at end of file