diff --git a/src/Xamarin.Android.Tools.AndroidSdk/AndroidVersions.cs b/src/Xamarin.Android.Tools.AndroidSdk/AndroidVersions.cs
index 9896288..e240aba 100644
--- a/src/Xamarin.Android.Tools.AndroidSdk/AndroidVersions.cs
+++ b/src/Xamarin.Android.Tools.AndroidSdk/AndroidVersions.cs
@@ -92,7 +92,8 @@ static bool MatchesFrameworkVersion (AndroidVersion version, string frameworkVer
 		public int? GetApiLevelFromId (string id)
 		{
 			return installedVersions.FirstOrDefault (v => MatchesId (v, id))?.ApiLevel ??
-				KnownVersions.FirstOrDefault (v => MatchesId (v, id))?.ApiLevel;
+				KnownVersions.FirstOrDefault (v => MatchesId (v, id))?.ApiLevel ??
+				(int.TryParse (id, out int apiLevel) ? apiLevel : default (int?));
 		}
 
 		static bool MatchesId (AndroidVersion version, string id)
@@ -105,7 +106,8 @@ static bool MatchesId (AndroidVersion version, string id)
 		public string? GetIdFromApiLevel (int apiLevel)
 		{
 			return installedVersions.FirstOrDefault (v => v.ApiLevel == apiLevel)?.Id ??
-				KnownVersions.FirstOrDefault (v => v.ApiLevel == apiLevel)?.Id;
+				KnownVersions.FirstOrDefault (v => v.ApiLevel == apiLevel)?.Id ??
+				apiLevel.ToString ();
 		}
 
 		// Sometimes, e.g. when new API levels are introduced, the "API level" is a letter, not a number,
@@ -115,7 +117,8 @@ static bool MatchesId (AndroidVersion version, string id)
 			if (int.TryParse (apiLevel, out var platform))
 				return GetIdFromApiLevel (platform);
 			return installedVersions.FirstOrDefault (v => MatchesId (v, apiLevel))?.Id ??
-				KnownVersions.FirstOrDefault (v => MatchesId (v, apiLevel))?.Id;
+				KnownVersions.FirstOrDefault (v => MatchesId (v, apiLevel))?.Id ??
+				apiLevel;
 		}
 
 		public string? GetIdFromFrameworkVersion (string frameworkVersion)
diff --git a/tests/Xamarin.Android.Tools.AndroidSdk-Tests/AndroidVersionsTests.cs b/tests/Xamarin.Android.Tools.AndroidSdk-Tests/AndroidVersionsTests.cs
index a3cd293..1ebe8f2 100644
--- a/tests/Xamarin.Android.Tools.AndroidSdk-Tests/AndroidVersionsTests.cs
+++ b/tests/Xamarin.Android.Tools.AndroidSdk-Tests/AndroidVersionsTests.cs
@@ -202,9 +202,9 @@ public void GetIdFromApiLevel ()
 			Assert.AreEqual ("II",  versions.GetIdFromApiLevel ("14"));
 			Assert.AreEqual ("II",  versions.GetIdFromApiLevel ("II"));
 
-			Assert.AreEqual (null,  versions.GetIdFromApiLevel (-1));
-			Assert.AreEqual (null,  versions.GetIdFromApiLevel ("-1"));
-			Assert.AreEqual (null,  versions.GetIdFromApiLevel ("D"));
+			Assert.AreEqual ("-1",  versions.GetIdFromApiLevel (-1));
+			Assert.AreEqual ("-1",  versions.GetIdFromApiLevel ("-1"));
+			Assert.AreEqual ("D",  versions.GetIdFromApiLevel ("D"));
 
 			// via KnownVersions
 			Assert.AreEqual ("11",  versions.GetIdFromApiLevel (11));