diff --git a/build.gradle b/build.gradle
index 273da48a94..ffbf71ffe9 100644
--- a/build.gradle
+++ b/build.gradle
@@ -157,7 +157,7 @@ subprojects {
 
     tasks.withType(JavaCompile) {
         options.encoding = 'UTF-8'
-        options.compilerArgs << '-Xlint:unchecked'
+        options.compilerArgs += '-Xlint:unchecked'
         options.deprecation = true
         options.incremental = true
     }
diff --git a/poi-ooxml-full/build.gradle b/poi-ooxml-full/build.gradle
index 81f38a8e0e..430153689d 100644
--- a/poi-ooxml-full/build.gradle
+++ b/poi-ooxml-full/build.gradle
@@ -51,7 +51,7 @@ final List MAIN_MODULE_PATH = sourceSets.main.runtimeClasspath.findAll{ it.path
 compileJava {
     dependsOn 'generate_beans'
     options.fork = true
-    options.forkOptions.jvmArgs << '-Xmx2G'
+    options.forkOptions.jvmArgs += '-Xmx2G'
 }
 
 task compileJava9(type: JavaCompile) {
diff --git a/poi-ooxml-lite/build.gradle b/poi-ooxml-lite/build.gradle
index 9122dba066..e9e046f2c5 100644
--- a/poi-ooxml-lite/build.gradle
+++ b/poi-ooxml-lite/build.gradle
@@ -83,7 +83,7 @@ task compileOoxmlLite(type: Copy) {
 compileJava {
     dependsOn 'compileOoxmlLite'
     options.fork = true
-    options.forkOptions.jvmArgs << '-Xmx2G'
+    options.forkOptions.jvmArgs += '-Xmx2G'
 }
 
 processResources.dependsOn 'compileOoxmlLite'
diff --git a/poi/build.gradle b/poi/build.gradle
index 649251f975..bf54b17b0a 100644
--- a/poi/build.gradle
+++ b/poi/build.gradle
@@ -175,7 +175,7 @@ test {
 
     doFirst {
         if (jdkVersion > 8) {
-            jvmArgs << [
+            jvmArgs += [
                 '--add-modules', MODULE_NAME,
                 '--module-path', '../build/dist/maven/poi-tests' + File.pathSeparator + files(MODULE_PATH).asPath,
             ]