diff --git a/java/config/kotlin.go b/java/config/kotlin.go
index fd8e3db..6cb61f3 100644
--- a/java/config/kotlin.go
+++ b/java/config/kotlin.go
@@ -35,11 +35,16 @@
 	pctx.SourcePathVariable("KotlinAnnotationJar", "external/kotlinc/lib/annotations-13.0.jar")
 	pctx.SourcePathVariable("KotlinStdlibJar", KotlinStdlibJar)
 
-	// These flags silence "Illegal reflective access" warnings when running kotlinc in OpenJDK9
-	pctx.StaticVariable("KotlincSuppressJDK9Warnings", strings.Join([]string{
+	// These flags silence "Illegal reflective access" warnings when running kapt in OpenJDK9+
+	pctx.StaticVariable("KaptSuppressJDK9Warnings", strings.Join([]string{
 		"-J--add-exports=jdk.compiler/com.sun.tools.javac.file=ALL-UNNAMED",
 		"-J--add-exports=jdk.compiler/com.sun.tools.javac.tree=ALL-UNNAMED",
 		"-J--add-exports=jdk.compiler/com.sun.tools.javac.main=ALL-UNNAMED",
 		"-J--add-opens=java.base/sun.net.www.protocol.jar=ALL-UNNAMED",
 	}, " "))
+
+	// These flags silence "Illegal reflective access" warnings when running kotlinc in OpenJDK9+
+	pctx.StaticVariable("KotlincSuppressJDK9Warnings", strings.Join([]string{
+		"-J--add-opens=java.base/java.util=ALL-UNNAMED", // https://youtrack.jetbrains.com/issue/KT-43704
+	}, " "))
 }
diff --git a/java/kotlin.go b/java/kotlin.go
index 2960f81..3a6fc0f 100644
--- a/java/kotlin.go
+++ b/java/kotlin.go
@@ -34,8 +34,9 @@
 			`${config.GenKotlinBuildFileCmd} --classpath "$classpath" --name "$name"` +
 			` --out_dir "$classesDir" --srcs "$out.rsp" --srcs "$srcJarDir/list"` +
 			` $commonSrcFilesArg --out "$kotlinBuildFile" && ` +
-			`${config.KotlincCmd} ${config.JavacHeapFlags} $kotlincFlags ` +
-			`-jvm-target $kotlinJvmTarget -Xbuild-file=$kotlinBuildFile -kotlin-home $emptyDir && ` +
+			`${config.KotlincCmd} ${config.KotlincSuppressJDK9Warnings} ${config.JavacHeapFlags} ` +
+			`$kotlincFlags -jvm-target $kotlinJvmTarget -Xbuild-file=$kotlinBuildFile ` +
+			`-kotlin-home $emptyDir && ` +
 			`${config.SoongZipCmd} -jar -o $out -C $classesDir -D $classesDir && ` +
 			`rm -rf "$srcJarDir"`,
 		CommandDeps: []string{
@@ -123,8 +124,8 @@
 			`${config.GenKotlinBuildFileCmd} --classpath "$classpath" --name "$name"` +
 			` --srcs "$out.rsp" --srcs "$srcJarDir/list"` +
 			` $commonSrcFilesArg --out "$kotlinBuildFile" && ` +
-			`${config.KotlincCmd} ${config.KotlincSuppressJDK9Warnings} ${config.JavacHeapFlags} $kotlincFlags ` +
-			`-Xplugin=${config.KotlinKaptJar} ` +
+			`${config.KotlincCmd} ${config.KaptSuppressJDK9Warnings} ${config.KotlincSuppressJDK9Warnings} ` +
+			`${config.JavacHeapFlags} $kotlincFlags -Xplugin=${config.KotlinKaptJar} ` +
 			`-P plugin:org.jetbrains.kotlin.kapt3:sources=$kaptDir/sources ` +
 			`-P plugin:org.jetbrains.kotlin.kapt3:classes=$kaptDir/classes ` +
 			`-P plugin:org.jetbrains.kotlin.kapt3:stubs=$kaptDir/stubs ` +