diff --git a/CHANGELOG.md b/CHANGELOG.md
index 09e86a3..9764d4f 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,5 +1,11 @@
 # Changelog
 
+## 6.4.1
+
+##### Fixes
+- threat empty circleCI environment variables as not set
+
+
 ## 6.4.0
 
 ##### Features
diff --git a/README.md b/README.md
index f730607..474af4a 100644
--- a/README.md
+++ b/README.md
@@ -28,7 +28,7 @@ This plugin can virtually set project version and properties, based on current *
 
 ```groovy
 plugins {
-    id 'me.qoomon.git-versioning' version '6.3.8'
+    id 'me.qoomon.git-versioning' version '6.4.1'
 }
 
 version = '0.0.0-SNAPSHOT'
@@ -41,7 +41,7 @@ gitVersioning.apply {
 
 ```kotlin
 plugins {
-    id("me.qoomon.git-versioning") version "6.3.8"
+    id("me.qoomon.git-versioning") version "6.4.1"
 }
 
 version = "0.0.0-SNAPSHOT"
diff --git a/build.gradle b/build.gradle
index a1eea07..01d886e 100644
--- a/build.gradle
+++ b/build.gradle
@@ -12,7 +12,7 @@ plugins {
 }
 
 group 'me.qoomon'
-version '6.4.0'
+version '6.4.1'
 sourceCompatibility = JavaVersion.VERSION_11
 targetCompatibility = JavaVersion.VERSION_11
 
diff --git a/src/main/java/me/qoomon/gradle/gitversioning/GitVersioningPluginExtension.java b/src/main/java/me/qoomon/gradle/gitversioning/GitVersioningPluginExtension.java
index eea59ef..7170194 100644
--- a/src/main/java/me/qoomon/gradle/gitversioning/GitVersioningPluginExtension.java
+++ b/src/main/java/me/qoomon/gradle/gitversioning/GitVersioningPluginExtension.java
@@ -39,8 +39,7 @@
 import static java.util.stream.Collectors.toList;
 import static me.qoomon.gitversioning.commons.GitRefType.*;
 import static me.qoomon.gitversioning.commons.StringUtil.*;
-import static org.apache.commons.lang3.StringUtils.leftPad;
-import static org.apache.commons.lang3.StringUtils.rightPad;
+import static org.apache.commons.lang3.StringUtils.*;
 import static org.eclipse.jgit.lib.Constants.HEAD;
 
 public abstract class GitVersioningPluginExtension {
@@ -351,11 +350,11 @@ private void handleEnvironment(Repository repository) throws IOException {
                     project.getLogger().debug("  CI_COMMIT_TAG: " + commitTag);
                     project.getLogger().debug("  CI_MERGE_REQUEST_SOURCE_BRANCH_NAME: " + mrSourceBranch);
 
-                    if (commitBranch != null) {
+                    if (!isBlank(commitBranch)) {
                         setBranch(commitBranch);
-                    } else if (mrSourceBranch != null) {
+                    } else if (!isBlank(mrSourceBranch)) {
                         setBranch(mrSourceBranch);
-                    } else if (commitTag != null) {
+                    } else if (!isBlank(commitTag)) {
                         addTag(commitTag);
                     }
                     return;
@@ -373,10 +372,10 @@ private void handleEnvironment(Repository repository) throws IOException {
                     project.getLogger().debug("  CIRCLE_BRANCH: " + commitBranch);
                     project.getLogger().debug("  CIRCLE_TAG: " + commitTag);
 
-                    if (commitBranch != null) {
-                        setBranch(commitBranch);
-                    } else if (commitTag != null) {
-                        addTag(commitTag);
+                    if (!isBlank(commitBranch)) {
+                        setBranch(commitBranch.trim());
+                    } else if (!isBlank(commitTag)) {
+                        addTag(commitTag.trim());
                     }
                     return;
                 }
@@ -392,13 +391,13 @@ private void handleEnvironment(Repository repository) throws IOException {
                     project.getLogger().debug("  BRANCH_NAME: " + commitBranch);
                     project.getLogger().debug("  TAG_NAME: " + commitTag);
 
-                    if (commitBranch != null) {
+                    if (!isBlank(commitBranch)) {
                         if (commitBranch.equals(commitTag)) {
                             addTag(commitBranch);
                         } else {
                             setBranch(commitBranch);
                         }
-                    } else if (commitTag != null) {
+                    } else if (!isBlank(commitTag)) {
                         addTag(commitTag);
                     }
                     return;