diff --git a/Octokit.Tests/Helpers/AssertEx.cs b/Octokit.Tests/Helpers/AssertEx.cs
index 66fda4b6..e8a062d3 100644
--- a/Octokit.Tests/Helpers/AssertEx.cs
+++ b/Octokit.Tests/Helpers/AssertEx.cs
@@ -51,7 +51,7 @@ namespace Octokit.Tests.Helpers
         {
             var collection = instance as ICollection<T>;
             // The collection == null case is for .NET 4.0
-            Assert.True(instance is IReadOnlyCollection<T> && (collection == null || collection.IsReadOnly));
+            Assert.True(instance is IReadOnlyList<T> && (collection == null || collection.IsReadOnly));
         }
     }
 }
diff --git a/Octokit/Models/Request/BaseSearchRequest.cs b/Octokit/Models/Request/BaseSearchRequest.cs
index be140d5f..5c9996c3 100644
--- a/Octokit/Models/Request/BaseSearchRequest.cs
+++ b/Octokit/Models/Request/BaseSearchRequest.cs
@@ -59,7 +59,7 @@ namespace Octokit
         /// <summary>
         /// All qualifiers that are used for this search
         /// </summary>
-        public abstract IReadOnlyCollection<string> MergedQualifiers();
+        public abstract IReadOnlyList<string> MergedQualifiers();
 
         /// <summary>
         /// Add qualifiers onto the search term
diff --git a/Octokit/Models/Request/SearchCodeRequest.cs b/Octokit/Models/Request/SearchCodeRequest.cs
index baacdc58..e28f5f1a 100644
--- a/Octokit/Models/Request/SearchCodeRequest.cs
+++ b/Octokit/Models/Request/SearchCodeRequest.cs
@@ -111,7 +111,7 @@ namespace Octokit
         public string Repo { get; set; }
 
         [SuppressMessage("Microsoft.Globalization", "CA1304:SpecifyCultureInfo", MessageId = "System.String.ToLower")]
-        public override IReadOnlyCollection<string> MergedQualifiers()
+        public override IReadOnlyList<string> MergedQualifiers()
         {
             var parameters = new List<string>();
 
diff --git a/Octokit/Models/Request/SearchIssuesRequest.cs b/Octokit/Models/Request/SearchIssuesRequest.cs
index 66376779..42c17234 100644
--- a/Octokit/Models/Request/SearchIssuesRequest.cs
+++ b/Octokit/Models/Request/SearchIssuesRequest.cs
@@ -176,7 +176,7 @@ namespace Octokit
         /// </remarks>
         public string Repo { get; set; }
 
-        public override IReadOnlyCollection<string> MergedQualifiers()
+        public override IReadOnlyList<string> MergedQualifiers()
         {
             var parameters = new List<string>();
 
diff --git a/Octokit/Models/Request/SearchRepositoriesRequest.cs b/Octokit/Models/Request/SearchRepositoriesRequest.cs
index 67aaf124..560c2b81 100644
--- a/Octokit/Models/Request/SearchRepositoriesRequest.cs
+++ b/Octokit/Models/Request/SearchRepositoriesRequest.cs
@@ -101,7 +101,7 @@ namespace Octokit
         /// </summary>
         public DateRange Updated { get; set; }
 
-        public override IReadOnlyCollection<string> MergedQualifiers()
+        public override IReadOnlyList<string> MergedQualifiers()
         {
             var parameters = new List<string>();
 
diff --git a/Octokit/Models/Request/SearchUsersRequest.cs b/Octokit/Models/Request/SearchUsersRequest.cs
index e5e6d062..66645f52 100644
--- a/Octokit/Models/Request/SearchUsersRequest.cs
+++ b/Octokit/Models/Request/SearchUsersRequest.cs
@@ -84,7 +84,7 @@ namespace Octokit
             }
         }
 
-        public override IReadOnlyCollection<string> MergedQualifiers()
+        public override IReadOnlyList<string> MergedQualifiers()
         {
             var parameters = new List<string>();
 
diff --git a/Octokit/Models/Response/CompareResult.cs b/Octokit/Models/Response/CompareResult.cs
index 2cac6d3d..7587852c 100644
--- a/Octokit/Models/Response/CompareResult.cs
+++ b/Octokit/Models/Response/CompareResult.cs
@@ -19,7 +19,7 @@ namespace Octokit
         public int AheadBy { get; protected set; }
         public int BehindBy { get; protected set; }
         public int TotalCommits { get; protected set; }
-        public IReadOnlyCollection<GitHubCommit> Commits { get; protected set; }
+        public IReadOnlyList<GitHubCommit> Commits { get; protected set; }
 
         internal string DebuggerDisplay
         {
diff --git a/Octokit/Models/Response/Contributor.cs b/Octokit/Models/Response/Contributor.cs
index 6d2e564c..36f28c07 100644
--- a/Octokit/Models/Response/Contributor.cs
+++ b/Octokit/Models/Response/Contributor.cs
@@ -15,7 +15,7 @@ namespace Octokit
 
         public int Total { get; protected set; }
 
-        public IEnumerable<WeeklyHash> Weeks { get; protected set; }
+        public IReadOnlyList<WeeklyHash> Weeks { get; protected set; }
 
         internal string DebuggerDisplay
         {
diff --git a/Octokit/Models/Response/Issue.cs b/Octokit/Models/Response/Issue.cs
index e7cadc96..b5bc16de 100644
--- a/Octokit/Models/Response/Issue.cs
+++ b/Octokit/Models/Response/Issue.cs
@@ -45,7 +45,7 @@ namespace Octokit
         /// <summary>
         /// The set of labels applied to the issue
         /// </summary>
-        public IReadOnlyCollection<Label> Labels { get; protected set; }
+        public IReadOnlyList<Label> Labels { get; protected set; }
 
         /// <summary>
         /// The user this issue is assigned to.
diff --git a/Octokit/Models/Response/OauthToken.cs b/Octokit/Models/Response/OauthToken.cs
index 5a4c9244..cf9a0635 100644
--- a/Octokit/Models/Response/OauthToken.cs
+++ b/Octokit/Models/Response/OauthToken.cs
@@ -21,7 +21,7 @@ namespace Octokit
         /// <summary>
         /// The list of scopes the token includes.
         /// </summary>
-        public IReadOnlyCollection<string> Scope { get; set; }
+        public IReadOnlyList<string> Scope { get; set; }
 
         internal string DebuggerDisplay
         {
diff --git a/Octokit/Models/Response/PunchCard.cs b/Octokit/Models/Response/PunchCard.cs
index af280163..7ed76243 100644
--- a/Octokit/Models/Response/PunchCard.cs
+++ b/Octokit/Models/Response/PunchCard.cs
@@ -20,7 +20,7 @@ namespace Octokit
         /// <summary>
         /// The raw punch card points
         /// </summary>
-        public IReadOnlyCollection<PunchCardPoint> PunchPoints { get; private set; }
+        public IReadOnlyList<PunchCardPoint> PunchPoints { get; private set; }
 
         /// <summary>
         /// Gets the number of commits made on the specified day of the week
diff --git a/Octokit/Models/Response/TreeResponse.cs b/Octokit/Models/Response/TreeResponse.cs
index 711baf5b..19414a04 100644
--- a/Octokit/Models/Response/TreeResponse.cs
+++ b/Octokit/Models/Response/TreeResponse.cs
@@ -22,7 +22,7 @@ namespace Octokit
         /// <summary>
         /// The list of Tree Items for this Tree response.
         /// </summary>
-        public IReadOnlyCollection<TreeItem> Tree { get; protected set; }
+        public IReadOnlyList<TreeItem> Tree { get; protected set; }
 
         internal string DebuggerDisplay
         {