diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 8b3f67a..55e9a96 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -28,7 +28,7 @@ jobs:
             cpu: arm64
           - os: windows
             cpu: amd64
-        branch: [version-2-0, version-2-2, devel]
+        branch: [version-1-6, version-2-0, version-2-2, devel]
         include:
           - target:
               os: linux
diff --git a/faststreams/buffers.nim b/faststreams/buffers.nim
index e35cf07..a76da33 100644
--- a/faststreams/buffers.nim
+++ b/faststreams/buffers.nim
@@ -59,7 +59,7 @@ func openArrayToPair*(a: var openArray[byte]): (ptr byte, Natural) =
   if a.len > 0:
     (addr a[0], Natural(a.len))
   else:
-    (nil, 0)
+    (nil, Natural(0))
 
 template allocationStart*(page: PageRef): ptr byte =
   baseAddr page.data[]