diff --git a/X10D.Tests/src/Linq/ReadOnlySpanTests.cs b/X10D.Tests/src/Linq/ReadOnlySpanTests.cs
index 942e646..2b6ab5f 100644
--- a/X10D.Tests/src/Linq/ReadOnlySpanTests.cs
+++ b/X10D.Tests/src/Linq/ReadOnlySpanTests.cs
@@ -76,7 +76,7 @@ internal class ReadOnlySpanTests
         Assert.Throws<ArgumentNullException>(() =>
         {
             var span = new ReadOnlySpan<int>();
-            _ = span.Count(null!);
+            _ = span.Count((Predicate<int>)null!);
         });
     }
 }
diff --git a/X10D.Tests/src/Linq/SpanTests.cs b/X10D.Tests/src/Linq/SpanTests.cs
index 313dea1..186d0e8 100644
--- a/X10D.Tests/src/Linq/SpanTests.cs
+++ b/X10D.Tests/src/Linq/SpanTests.cs
@@ -76,7 +76,7 @@ internal class SpanTests
         Assert.Throws<ArgumentNullException>(() =>
         {
             var span = new Span<int>();
-            _ = span.Count(null!);
+            _ = span.Count((Predicate<int>)null!);
         });
     }
 }