diff --git a/.editorconfig b/.editorconfig
index 2b46995..f14b998 100644
--- a/.editorconfig
+++ b/.editorconfig
@@ -1,4 +1,4 @@
-# Copyright © 2019 Peter M. Stahl pemistahl@gmail.com
+# Copyright © 2019-2020 Peter M. Stahl pemistahl@gmail.com
 #
 # Licensed under the Apache License, Version 2.0 (the "License");
 # you may not use this file except in compliance with the License.
diff --git a/.gitignore b/.gitignore
index ee88980..07fe3e8 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,4 +1,4 @@
-# Copyright © 2019 Peter M. Stahl pemistahl@gmail.com
+# Copyright © 2019-2020 Peter M. Stahl pemistahl@gmail.com
 #
 # Licensed under the Apache License, Version 2.0 (the "License");
 # you may not use this file except in compliance with the License.
diff --git a/.travis.yml b/.travis.yml
index bbaa0e7..168dea4 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -1,5 +1,5 @@
 #
-# Copyright © 2019 Peter M. Stahl pemistahl@gmail.com
+# Copyright © 2019-2020 Peter M. Stahl pemistahl@gmail.com
 #
 # Licensed under the Apache License, Version 2.0 (the "License");
 # you may not use this file except in compliance with the License.
diff --git a/Cargo.toml b/Cargo.toml
index 6ae4c7c..112c7ba 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -1,4 +1,4 @@
-# Copyright © 2019 Peter M. Stahl pemistahl@gmail.com
+# Copyright © 2019-2020 Peter M. Stahl pemistahl@gmail.com
 #
 # Licensed under the Apache License, Version 2.0 (the "License");
 # you may not use this file except in compliance with the License.
diff --git a/RELEASE_NOTES.md b/RELEASE_NOTES.md
index 884ff12..5cd0aee 100644
--- a/RELEASE_NOTES.md
+++ b/RELEASE_NOTES.md
@@ -1,3 +1,17 @@
+## grex 0.3.1 (released on 06 Jan 2020)
+
+### Test Coverage
+- property tests have been added using the [proptest](https://crates.io/crates/proptest) crate 
+- big thanks go to [Christophe Biocca](https://github.com/christophebiocca) for pointing me to the concept of property tests in the first place and for writing an initial implementation of these tests
+
+### Bug Fixes
+- some regular expression specific characters were not escaped correctly in the generated expression
+- expressions consisting of a single alternation such as `^(abc|xyz)$` were missing the outer parentheses. This caused an erroneous match of strings such as `abc123` or `456xyz` because of precedence rules.
+- the created DFA was wrong for repetition conversion in some corner cases. The input `a, aa, aaa, aaaa, aaab` previously returned the expression `^a{1,4}b?$` which erroneously matches `aaaab`. Now the correct expression `^(a{3}b|a{1,4})$` is returned.
+
+### Documentation
+- some minor documentation updates
+
 ## grex 0.3.0 (released on 24 Dec 2019)
 
 ### Features
diff --git a/src/ast.rs b/src/ast.rs
index 5d6d576..7534eba 100644
--- a/src/ast.rs
+++ b/src/ast.rs
@@ -1,5 +1,5 @@
 /*
- * Copyright © 2019 Peter M. Stahl pemistahl@gmail.com
+ * Copyright © 2019-2020 Peter M. Stahl pemistahl@gmail.com
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
diff --git a/src/dfa.rs b/src/dfa.rs
index 782aa75..2d5446c 100644
--- a/src/dfa.rs
+++ b/src/dfa.rs
@@ -1,5 +1,5 @@
 /*
- * Copyright © 2019 Peter M. Stahl pemistahl@gmail.com
+ * Copyright © 2019-2020 Peter M. Stahl pemistahl@gmail.com
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
diff --git a/src/fmt.rs b/src/fmt.rs
index 3896965..3398027 100644
--- a/src/fmt.rs
+++ b/src/fmt.rs
@@ -1,5 +1,5 @@
 /*
- * Copyright © 2019 Peter M. Stahl pemistahl@gmail.com
+ * Copyright © 2019-2020 Peter M. Stahl pemistahl@gmail.com
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
diff --git a/src/grapheme.rs b/src/grapheme.rs
index 11274ac..1e5a684 100644
--- a/src/grapheme.rs
+++ b/src/grapheme.rs
@@ -1,5 +1,5 @@
 /*
- * Copyright © 2019 Peter M. Stahl pemistahl@gmail.com
+ * Copyright © 2019-2020 Peter M. Stahl pemistahl@gmail.com
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
diff --git a/src/lib.rs b/src/lib.rs
index b029694..54d71d7 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -1,5 +1,5 @@
 /*
- * Copyright © 2019 Peter M. Stahl pemistahl@gmail.com
+ * Copyright © 2019-2020 Peter M. Stahl pemistahl@gmail.com
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
diff --git a/src/macros.rs b/src/macros.rs
index 28763e6..11764e3 100644
--- a/src/macros.rs
+++ b/src/macros.rs
@@ -1,5 +1,5 @@
 /*
- * Copyright © 2019 Peter M. Stahl pemistahl@gmail.com
+ * Copyright © 2019-2020 Peter M. Stahl pemistahl@gmail.com
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
diff --git a/src/main.rs b/src/main.rs
index f87dcb5..a453862 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -1,5 +1,5 @@
 /*
- * Copyright © 2019 Peter M. Stahl pemistahl@gmail.com
+ * Copyright © 2019-2020 Peter M. Stahl pemistahl@gmail.com
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
diff --git a/src/regexp.rs b/src/regexp.rs
index be3ed1d..79694dd 100644
--- a/src/regexp.rs
+++ b/src/regexp.rs
@@ -1,5 +1,5 @@
 /*
- * Copyright © 2019 Peter M. Stahl pemistahl@gmail.com
+ * Copyright © 2019-2020 Peter M. Stahl pemistahl@gmail.com
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
diff --git a/tests/cli_integration_tests.rs b/tests/cli_integration_tests.rs
index d245e5d..913c39e 100644
--- a/tests/cli_integration_tests.rs
+++ b/tests/cli_integration_tests.rs
@@ -1,5 +1,5 @@
 /*
- * Copyright © 2019 Peter M. Stahl pemistahl@gmail.com
+ * Copyright © 2019-2020 Peter M. Stahl pemistahl@gmail.com
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
diff --git a/tests/lib_integration_tests.rs b/tests/lib_integration_tests.rs
index 86b601a..e7979f4 100644
--- a/tests/lib_integration_tests.rs
+++ b/tests/lib_integration_tests.rs
@@ -1,5 +1,5 @@
 /*
- * Copyright © 2019 Peter M. Stahl pemistahl@gmail.com
+ * Copyright © 2019-2020 Peter M. Stahl pemistahl@gmail.com
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
diff --git a/tests/property_tests.rs b/tests/property_tests.rs
index 70331b0..6fcdba0 100644
--- a/tests/property_tests.rs
+++ b/tests/property_tests.rs
@@ -1,5 +1,5 @@
 /*
- * Copyright © 2019 Peter M. Stahl pemistahl@gmail.com
+ * Copyright © 2019-2020 Peter M. Stahl pemistahl@gmail.com
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.