diff --git a/src/app.rs b/src/app.rs
index 3c3ba3c..e557b2a 100644
--- a/src/app.rs
+++ b/src/app.rs
@@ -66,7 +66,11 @@ pub struct App {
     pub launcher_path: Option<PathBuf>,
     pub state_flags: Option<StateFlags>,
     // TODO: Need to handle this for serializing too before `App` can `impl Serialize`
-    #[serde(default, deserialize_with = "de_time_as_secs_from_unix_epoch")]
+    #[serde(
+        alias = "lastupdated",
+        default,
+        deserialize_with = "de_time_as_secs_from_unix_epoch"
+    )]
     pub last_updated: Option<time::SystemTime>,
     // Can't find anything on what these values mean. I've seen 0, 2, 4, 6, and 7
     pub update_result: Option<u64>,
diff --git a/src/tests/helpers.rs b/src/tests/helpers.rs
index 6982956..ce175c5 100644
--- a/src/tests/helpers.rs
+++ b/src/tests/helpers.rs
@@ -255,9 +255,11 @@ impl AppFile {
     }
 }
 
+#[derive(Clone, Copy)]
 pub enum SampleApp {
     GarrysMod,
     GraveyardKeeper,
+    Resonite,
     Warframe,
 }
 
@@ -286,6 +288,11 @@ impl SampleApp {
                 "Graveyard Keeper",
                 include_str!("../../tests/assets/appmanifest_599140.acf"),
             ),
+            Self::Resonite => (
+                2_519_830,
+                "Resonite",
+                include_str!("../../tests/assets/appmanifest_2519830.acf"),
+            ),
             Self::Warframe => (
                 230_410,
                 "Warframe",
diff --git a/src/tests/mod.rs b/src/tests/mod.rs
index 6d036c2..9df106d 100644
--- a/src/tests/mod.rs
+++ b/src/tests/mod.rs
@@ -3,6 +3,8 @@ pub mod helpers;
 mod legacy;
 mod temp;
 #[cfg(test)]
+mod tests;
+#[cfg(test)]
 mod wasm;
 
 pub type TestError = Box<dyn std::error::Error>;
diff --git a/src/tests/tests.rs b/src/tests/tests.rs
new file mode 100644
index 0000000..f98454e
--- /dev/null
+++ b/src/tests/tests.rs
@@ -0,0 +1,18 @@
+use crate::tests::{
+    helpers::{SampleApp, TempSteamDir},
+    TestResult,
+};
+
+// Context: https://github.com/WilliamVenner/steamlocate-rs/issues/58
+#[test]
+fn app_lastupdated_casing() -> TestResult {
+    let sample_app = SampleApp::Resonite;
+    let temp_steam_dir = TempSteamDir::builder().app(sample_app.into()).finish()?;
+    let steam_dir = temp_steam_dir.steam_dir();
+
+    let (app, _library) = steam_dir.find_app(sample_app.id())?.unwrap();
+    // Last updated _should_ be `Some(_)` for this app even though it uses lowercase casing
+    let _ = app.last_updated.unwrap();
+
+    Ok(())
+}
diff --git a/tests/assets/appmanifest_2519830.acf b/tests/assets/appmanifest_2519830.acf
new file mode 100644
index 0000000..5610c7f
--- /dev/null
+++ b/tests/assets/appmanifest_2519830.acf
@@ -0,0 +1,50 @@
+"AppState"
+{
+	"appid"		"2519830"
+	"Universe"		"1"
+	"name"		"Resonite"
+	"StateFlags"		"4"
+	"installdir"		"Resonite"
+	"lastupdated"		"1702688752"
+	"SizeOnDisk"		"1102323116"
+	"StagingSize"		"0"
+	"buildid"		"12967476"
+	"LastOwner"		"76561198022773299"
+	"UpdateResult"		"0"
+	"BytesToDownload"		"2332576"
+	"BytesDownloaded"		"2332576"
+	"BytesToStage"		"54625540"
+	"BytesStaged"		"54625540"
+	"TargetBuildID"		"12967476"
+	"AutoUpdateBehavior"		"0"
+	"AllowOtherDownloadsWhileRunning"		"0"
+	"ScheduledAutoUpdate"		"0"
+	"InstalledDepots"
+	{
+		"2519832"
+		{
+			"manifest"		"1396658363472368690"
+			"size"		"514493538"
+		}
+		"2519831"
+		{
+			"manifest"		"5082223756179978205"
+			"size"		"587829578"
+		}
+	}
+	"SharedDepots"
+	{
+		"228984"		"228980"
+		"228985"		"228980"
+		"228988"		"228980"
+		"228989"		"228980"
+	}
+	"UserConfig"
+	{
+		"language"		"english"
+	}
+	"MountedConfig"
+	{
+		"language"		"english"
+	}
+}