diff --git a/src/FSharp.Control.AsyncSeq/AsyncSeq.fs b/src/FSharp.Control.AsyncSeq/AsyncSeq.fs
index f749ea7b..6ec35694 100644
--- a/src/FSharp.Control.AsyncSeq/AsyncSeq.fs
+++ b/src/FSharp.Control.AsyncSeq/AsyncSeq.fs
@@ -1700,8 +1700,9 @@ module AsyncSeq =
 
   /// Merges all specified async sequences into an async sequence non-deterministically.
   // By moving the last emitted task to the end of the array, this algorithm achieves max-min fairness when merging AsyncSeqs
-  let mergeAll (ss:AsyncSeq<'T> list) : AsyncSeq<'T> =
+  let mergeAll (ss:seq<AsyncSeq<'T>>) : AsyncSeq<'T> =
     asyncSeq {
+      let ss = Seq.toArray ss
       let n = ss.Length
 
       let moveToEnd i (a: 'a[]) =
diff --git a/src/FSharp.Control.AsyncSeq/AsyncSeq.fsi b/src/FSharp.Control.AsyncSeq/AsyncSeq.fsi
index 15c1bf56..78504ea9 100644
--- a/src/FSharp.Control.AsyncSeq/AsyncSeq.fsi
+++ b/src/FSharp.Control.AsyncSeq/AsyncSeq.fsi
@@ -502,7 +502,7 @@ module AsyncSeq =
 
     /// Merges all specified async sequences into an async sequence non-deterministically.
     /// The resulting async sequence produces elements when any argument sequence produces an element.
-    val mergeAll : sources:AsyncSeq<'T> list -> AsyncSeq<'T>
+    val mergeAll : sources:seq<AsyncSeq<'T>> -> AsyncSeq<'T>
     #endif
 
     /// Returns an async sequence which contains no contiguous duplicate elements based on the specified comparison function.