1 files changed, 4 insertions, 0 deletions
diff --git a/main/src/core/MonoDevelop.Core/MonoDevelop.Projects/AssemblyReference.cs b/main/src/core/MonoDevelop.Core/MonoDevelop.Projects/AssemblyReference.cs
index 67c93fb9c5..f9b4e67a9f 100644
--- a/main/src/core/MonoDevelop.Core/MonoDevelop.Projects/AssemblyReference.cs
+++ b/main/src/core/MonoDevelop.Core/MonoDevelop.Projects/AssemblyReference.cs
@@ -139,6 +139,10 @@ namespace MonoDevelop.Projects
 
 		public SolutionItem GetReferencedItem (Solution parentSolution)
 		{
+			if (parentSolution is null) {
+				throw new ArgumentNullException (nameof (parentSolution));
+			}
+
 			var projectPath = GetMetadata ("MSBuildSourceProjectFile");
 			if (!string.IsNullOrEmpty (projectPath)) {
 				var project = parentSolution.FindSolutionItem (projectPath);