diff --git a/OpenRA.Mods.Common/Installer/SourceResolvers/GogSourceResolver.cs b/OpenRA.Mods.Common/Installer/SourceResolvers/GogSourceResolver.cs
index 4f4f3dd74b..74a1a9b305 100644
--- a/OpenRA.Mods.Common/Installer/SourceResolvers/GogSourceResolver.cs
+++ b/OpenRA.Mods.Common/Installer/SourceResolvers/GogSourceResolver.cs
@@ -34,8 +34,13 @@ namespace OpenRA.Mods.Common.Installer
 			var prefixes = new[] { "HKEY_LOCAL_MACHINE\\Software\\", "HKEY_LOCAL_MACHINE\\SOFTWARE\\Wow6432Node\\" };
 
 			foreach (var prefix in prefixes)
-				if (Registry.GetValue($"{prefix}GOG.com\\Games\\{appId.Value}", "path", null) is string installDir)
+			{
+				if (!(Registry.GetValue($"{prefix}GOG.com\\Games\\{appId.Value}", "path", null) is string installDir))
+					continue;
+
+				if (InstallerUtils.IsValidSourcePath(installDir, modSource))
 					return installDir;
+			}
 
 			return null;
 		}
diff --git a/OpenRA.Mods.Common/Installer/SourceResolvers/SteamSourceResolver.cs b/OpenRA.Mods.Common/Installer/SourceResolvers/SteamSourceResolver.cs
index b86de2adb8..712bdd1f8d 100644
--- a/OpenRA.Mods.Common/Installer/SourceResolvers/SteamSourceResolver.cs
+++ b/OpenRA.Mods.Common/Installer/SourceResolvers/SteamSourceResolver.cs
@@ -43,8 +43,13 @@ namespace OpenRA.Mods.Common.Installer
 				if (!data.TryGetValue("installdir", out var installDir))
 					continue;
 
-				if (installDir != null)
-					return Path.Combine(steamDirectory, "steamapps", "common", installDir);
+				if (installDir == null)
+					continue;
+
+				var path = Path.Combine(steamDirectory, "steamapps", "common", installDir);
+
+				if (InstallerUtils.IsValidSourcePath(path, modSource))
+					return path;
 			}
 
 			return null;