diff --git a/ICSharpCode.Decompiler/Metadata/DotNetCorePathFinderExtensions.cs b/ICSharpCode.Decompiler/Metadata/DotNetCorePathFinderExtensions.cs
index ca241ca9c9..088d673d12 100644
--- a/ICSharpCode.Decompiler/Metadata/DotNetCorePathFinderExtensions.cs
+++ b/ICSharpCode.Decompiler/Metadata/DotNetCorePathFinderExtensions.cs
@@ -72,13 +72,16 @@ public static string DetectTargetFrameworkId(this PEReader assembly, string asse
 				}
 			}
 
-			var thisAssemblyName = reader.GetAssemblyDefinition().GetAssemblyName();
-			switch (thisAssemblyName.Name)
+			if (reader.IsAssembly)
 			{
-				case "mscorlib":
-					return $".NETFramework,Version=v{thisAssemblyName.Version.ToString(2)}";
-				case "netstandard":
-					return $".NETStandard,Version=v{thisAssemblyName.Version.ToString(2)}";
+				var thisAssemblyName = reader.GetAssemblyDefinition().GetAssemblyName();
+				switch (thisAssemblyName.Name)
+				{
+					case "mscorlib":
+						return $".NETFramework,Version=v{thisAssemblyName.Version.ToString(2)}";
+					case "netstandard":
+						return $".NETStandard,Version=v{thisAssemblyName.Version.ToString(2)}";
+				}
 			}
 
 			foreach (var h in reader.AssemblyReferences)