diff --git a/CHANGELOG.md b/CHANGELOG.md
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,3 +1,7 @@
+1.3.1
+
+* BUG FIX: `asin` now correctly delegates to `fmap asin` and not `fmap sin`
+
 1.3.0
 
 * BREAKING CHANGE: Change `vector` to be a pure `Fold` (which is faster, too!)
diff --git a/README.md b/README.md
--- a/README.md
+++ b/README.md
@@ -1,4 +1,4 @@
-# `foldl` v1.3.0
+# `foldl` v1.3.1
 
 Use this `foldl` library when you want to compute multiple folds over a
 collection in one pass over the data without space leaks.
diff --git a/foldl.cabal b/foldl.cabal
--- a/foldl.cabal
+++ b/foldl.cabal
@@ -1,5 +1,5 @@
 Name: foldl
-Version: 1.3.0
+Version: 1.3.1
 Cabal-Version: >=1.8.0.2
 Build-Type: Simple
 License: BSD3
@@ -32,7 +32,7 @@
         text         >= 0.11.2.0 && < 1.3 ,
         transformers >= 0.2.0.0  && < 0.6 ,
         vector       >= 0.7      && < 0.13,
-        containers                  < 0.6 ,
+        containers   >= 0.5.0.0  && < 0.6 ,
         unordered-containers        < 0.3 ,
         hashable                    < 1.3 ,
         contravariant               < 1.5 ,
diff --git a/src/Control/Foldl.hs b/src/Control/Foldl.hs
--- a/src/Control/Foldl.hs
+++ b/src/Control/Foldl.hs
@@ -418,7 +418,7 @@
     cos = fmap cos
     {-# INLINE cos #-}
 
-    asin = fmap sin
+    asin = fmap asin
     {-# INLINE asin #-}
 
     atan = fmap atan