diff --git a/CHANGES b/CHANGES
index 55f18b9b2..882b5f976 100644
--- a/CHANGES
+++ b/CHANGES
@@ -3,9 +3,12 @@
 
 Following is a brief summary of changes made in each release of Libint.
 
-- 2017-xx-yy: 2.4.0
+- 2017-xx-yy: 2.3.2
   -
 
+- 2017-05-03: 2.3.1
+  - minor fixes to libint2::any
+
 - 2017-05-02: 2.3.0
   - bumped the compiler source license to GPLv3, generated code is LGPLv3.
   - replaced non-standard-conforming libint2::any with a homegrown C++17-conforming any;
diff --git a/CITATION b/CITATION
index 43949659b..1b4bd6174 100644
--- a/CITATION
+++ b/CITATION
@@ -4,12 +4,12 @@ If you publish results using LIBINT, please cite it using:
 
 An unmodified standard release:
 
-Libint: A library for the evaluation of molecular integrals of many-body operators over Gaussian functions, Version 2.3.0
+Libint: A library for the evaluation of molecular integrals of many-body operators over Gaussian functions, Version 2.3.1
 Edward F. Valeev, http://libint.valeyev.net/ .
 
 A modified release:
 
-Libint: A library for the evaluation of molecular integrals of many-body operators over Gaussian functions, Version 2.3.0
+Libint: A library for the evaluation of molecular integrals of many-body operators over Gaussian functions, Version 2.3.1
 Edward F. Valeev, http://libint.valeyev.net/ . Modified by An Author, institution, location, year.
 
 The literature citation in bibtex format is:
@@ -18,7 +18,7 @@ The literature citation in bibtex format is:
   author = "E.~F.~Valeev",
   title = “Libint: A library for the evaluation of molecular integrals of many-body operators over Gaussian functions",
   howpublished = "http://libint.valeyev.net/",
-  note = "version 2.3.0",
+  note = "version 2.3.1",
   year =         2017
 }
 
diff --git a/configure.ac b/configure.ac
index 6ee7c5c46..09cd22bc9 100644
--- a/configure.ac
+++ b/configure.ac
@@ -1,4 +1,4 @@
-define([libint_mmm_version],[2.3.0])
+define([libint_mmm_version],[2.3.1])
 define([libint_buildid],[])
 define([libint_so_version],[2:2:0])
 
diff --git a/export/configure.export b/export/configure.export
index 74d3024d0..108a9a913 100644
--- a/export/configure.export
+++ b/export/configure.export
@@ -1,4 +1,4 @@
-define([libint_mmm_version],[2.3.0])
+define([libint_mmm_version],[2.3.1])
 define([libint_buildid],[])
 define([libint_so_version],[2:2:0])
 
diff --git a/include/libint2/util/any.h b/include/libint2/util/any.h
index 0d5555a0e..392be280f 100644
--- a/include/libint2/util/any.h
+++ b/include/libint2/util/any.h
@@ -33,6 +33,14 @@ namespace libint2 {
 #if __cplusplus >= 201703L
 using std::any;
 #else
+
+namespace detail {
+// true if decayed T is Base, or is derived from it
+template <typename Base, typename T>
+using disable_if_same_or_derived = typename std::enable_if<
+    !std::is_base_of<Base, typename std::decay<T>::type>::value>::type;
+};
+
 /// a partial C++17 std::any implementation (and less efficient than can be)
 class any {
  public:
@@ -40,7 +48,8 @@ class any {
   any() : impl_(nullptr) {}
   any(const any& other) : impl_(other.impl_->clone()) {}
   any(any&& other) = default;
-  template <class ValueType>
+  template <typename ValueType,
+            typename = detail::disable_if_same_or_derived<any, ValueType> >
   any(ValueType&& value)
       : impl_(new impl<typename std::decay<ValueType>::type>(
             std::forward<ValueType>(value))) {}
@@ -54,9 +63,10 @@ class any {
     impl_ = std::move(rhs.impl_);
     return *this;
   }
-  template<typename ValueType>
-  any& operator=( ValueType&& rhs ) {
-    impl_ = decltype(impl_)(new impl<typename std::decay<ValueType>::type> (
+  template <typename ValueType,
+            typename = detail::disable_if_same_or_derived<any, ValueType> >
+  any& operator=(ValueType&& rhs) {
+    impl_ = decltype(impl_)(new impl<typename std::decay<ValueType>::type>(
         std::forward<ValueType>(rhs)));
     return *this;
   }