diff --git a/entrypoint.sh b/entrypoint.sh
index 61c5791..4b47069 100755
--- a/entrypoint.sh
+++ b/entrypoint.sh
@@ -10,6 +10,7 @@ REPO="${INPUT_REPO:-reviewdog/reviewdog}"
 VERSION_NAME="${INPUT_VERSION_NAME:-REVIEWDOG_VERSION}"
 
 # Get current version.
+# NOTE: Go to https://regex101.com/r/t1JcmL/13 To see the current regex in action.
 CURRENT_VERSION=$(grep -oP "${VERSION_NAME}(?:\s*=\s*|:?\s*)[\"|\']?v?\K\d+\.\d+(\.\d+)?(-[^\'\"\s]*)?" "${FILE}" | head -n1)
 if [ -z "${CURRENT_VERSION}" ]; then
   echo "cannot parse ${VERSION_NAME}"
diff --git a/testdata/testfile b/testdata/testfile
index f8234c4..8146a6f 100644
--- a/testdata/testfile
+++ b/testdata/testfile
@@ -1,22 +1,32 @@
 This is test file.
 
-REVIEWDOG_VERSION=v0.11.0
-REVIEWDOG_VERSION = v0.11.0
-REVIEWDOG_VERSION=0.11.0
-REVIEWDOG_VERSION = 0.11.0
-REVIEWDOG_VERSION="v0.11.0"
-REVIEWDOG_VERSION = "v0.11.0"
-REVIEWDOG_VERSION="0.11.0"
-REVIEWDOG_VERSION = "0.11.0"
-REVIEWDOG_VERSION="v0.11.0"
-REVIEWDOG_VERSION = "v0.11.0"
-REVIEWDOG_VERSION="0.11.0"
-REVIEWDOG_VERSION = "0.11.0"
-ENV REVIEWDOG_VERSION=0.11.0
-ENV REVIEWDOG_VERSION 0.11.0
-ARG REVIEWDOG_VERSION=0.11.0
+REVIEWDOG_VERSION=v0.1.0
+REVIEWDOG_VERSION = v0.1.0
+REVIEWDOG_VERSION=0.1.0
+REVIEWDOG_VERSION = 0.1.0
+REVIEWDOG_VERSION="v0.1.0"
+REVIEWDOG_VERSION='v0.1.0'
+REVIEWDOG_VERSION = "v0.1.0"
+REVIEWDOG_VERSION = 'v0.1.0'
+REVIEWDOG_VERSION="0.1.0"
+REVIEWDOG_VERSION='0.1.0'
+REVIEWDOG_VERSION = "0.1.0"
+REVIEWDOG_VERSION = '0.1.0'
+REVIEWDOG_VERSION="v0.1.0-nightly20201208+12faa31"
+REVIEWDOG_VERSION='v0.1.0-nightly20201208+12faa31'
+REVIEWDOG_VERSION = "v0.1.0-nightly20201208+12faa31"
+REVIEWDOG_VERSION = 'v0.1.0-nightly20201208+12faa31'
+REVIEWDOG_VERSION="0.1.0-nightly20201208+12faa31"
+REVIEWDOG_VERSION='0.1.0-nightly20201208+12faa31'
+REVIEWDOG_VERSION = "0.1.0-nightly20201208+12faa31"
+REVIEWDOG_VERSION = '0.1.0-nightly20201208+12faa31'
+ENV REVIEWDOG_VERSION=0.1.0
+ENV REVIEWDOG_VERSION 0.1.0
+ARG REVIEWDOG_VERSION=0.1.0
 yaml:
-  REVIEWDOG_VERSION: 0.11.0
+  REVIEWDOG_VERSION: 0.1.0
+  REVIEWDOG_VERSION: "0.1.0"
+  REVIEWDOG_VERSION: '0.1.0'
 
 The above version should be updated to the latest version with this action.