diff --git a/src/System.Collections.Immutable/src/System/Collections/Immutable/ImmutableArray`1+Builder.cs b/src/System.Collections.Immutable/src/System/Collections/Immutable/ImmutableArray`1+Builder.cs
index 03b4d1e466b3..bfea4d97a46e 100644
--- a/src/System.Collections.Immutable/src/System/Collections/Immutable/ImmutableArray`1+Builder.cs
+++ b/src/System.Collections.Immutable/src/System/Collections/Immutable/ImmutableArray`1+Builder.cs
@@ -39,6 +39,7 @@ public sealed class Builder : IList<T>, IReadOnlyList<T>
             /// <param name="capacity">The initial capacity of the internal array.</param>
             internal Builder(int capacity)
             {
+                Requires.Range(capacity >= 0, "capacity");
                 this.elements = new RefAsValueType<T>[capacity];
                 this.Count = 0;
             }
diff --git a/src/System.Collections.Immutable/tests/ImmutableArrayBuilderTest.cs b/src/System.Collections.Immutable/tests/ImmutableArrayBuilderTest.cs
index 9347a54603b7..89fd67bf1cb5 100644
--- a/src/System.Collections.Immutable/tests/ImmutableArrayBuilderTest.cs
+++ b/src/System.Collections.Immutable/tests/ImmutableArrayBuilderTest.cs
@@ -20,6 +20,12 @@ public void CreateBuilderDefaultCapacity()
             Assert.NotSame(builder, ImmutableArray.CreateBuilder<int>());
         }
 
+        [Fact]
+        public void CreateBuilderInvalidCapacity()
+        {
+            Assert.Throws<ArgumentOutOfRangeException>(() => ImmutableArray.CreateBuilder<int>(-1));
+        }
+
         [Fact]
         public void NormalConstructionValueType()
         {