diff --git a/brut.apktool/apktool-cli/build.gradle b/brut.apktool/apktool-cli/build.gradle
index 9cd987ad..be0076b0 100644
--- a/brut.apktool/apktool-cli/build.gradle
+++ b/brut.apktool/apktool-cli/build.gradle
@@ -37,7 +37,7 @@ buildscript {
 
 jar {
     manifest {
-        attributes 'Main-Class' : 'brut.apktool.Main'
+        attributes 'Main-Class': 'brut.apktool.Main'
     }
 }
 
@@ -73,6 +73,8 @@ task proguard(type: ProGuardTask, dependsOn: shadowJar) {
     dontwarn 'com.google.common.util.**'
     dontwarn 'javax.xml.xpath.**'
     dontnote '**'
+    // between Java 1.8 and 1.9, the signature of `flip()` changed, which trips up proguard.
+    dontwarn 'org.yaml.snakeyaml.scanner.ScannerImpl'
 
     def outPath = jar.getDestinationDirectory().getAsFile().get().toString()
     def extension = jar.archiveExtension.get().toString()
@@ -81,4 +83,4 @@ task proguard(type: ProGuardTask, dependsOn: shadowJar) {
 }
 
 proguard.dependsOn cleanOutputDirectory
-tasks.getByPath(':release').dependsOn(proguard)
\ No newline at end of file
+tasks.getByPath(':release').dependsOn(proguard)