diff --git a/apps/chown.cpp b/apps/chown.cpp
index 36f88b7e..c3b3ff58 100644
--- a/apps/chown.cpp
+++ b/apps/chown.cpp
@@ -1,24 +1,78 @@
+#include <luna/String.h>
 #include <os/ArgumentParser.h>
+#include <pwd.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <unistd.h>
 
-int main(int argc, char** argv)
+Result<int> luna_main(int argc, char** argv)
 {
-    StringView user;
+    StringView user_and_group;
     StringView path;
 
     os::ArgumentParser parser;
     parser.add_description("Change the owner and group of a file."_sv);
-    parser.add_positional_argument(user, "user"_sv, true);
+    parser.add_positional_argument(user_and_group, "owner"_sv, true);
     parser.add_positional_argument(path, "path"_sv, true);
     parser.parse(argc, argv);
 
-    u32 id = (u32)strtoul(user.chars(), NULL, 0);
+    u32 uid = -1;
+    Option<u32> gid = -1;
 
-    if (chown(path.chars(), id, id) < 0)
+    auto names = TRY(user_and_group.split_once(':'));
+    if (names.size() > 1)
+    {
+        auto& group = names[1];
+        if (group.is_empty()) { gid = {}; }
+        else
+        {
+            auto rc = group.view().to_uint();
+            if (rc.has_value()) { gid = (u32)rc.value(); }
+            else
+            {
+                fprintf(stderr, "FIXME: read entry from group file to determine GID for group %s\n", group.chars());
+                return 1;
+            }
+        }
+    }
+    if (names.size() > 0)
+    {
+        auto& owner = names[0];
+        if (!owner.is_empty())
+        {
+            auto rc = owner.view().to_uint();
+            if (rc.has_value()) { uid = (u32)rc.value(); }
+            else
+            {
+                struct passwd* pw = getpwnam(owner.chars());
+                if (!pw)
+                {
+                    fprintf(stderr, "%s: unknown user %s!\n", argv[0], owner.chars());
+                    return 1;
+                }
+
+                uid = pw->pw_uid;
+            }
+
+            if (!gid.has_value())
+            {
+                struct passwd* pw = getpwuid(uid);
+                if (!pw)
+                {
+                    fprintf(stderr, "%s: unknown user id %u!\n", argv[0], uid);
+                    return 1;
+                }
+
+                gid = pw->pw_gid;
+            }
+        }
+    }
+
+    if (chown(path.chars(), uid, gid.value_or(-1)) < 0)
     {
         perror("chown");
         return 1;
     }
+
+    return 0;
 }