diff --git a/android/config.go b/android/config.go
index 42a286c..8b5ede6 100644
--- a/android/config.go
+++ b/android/config.go
@@ -1362,13 +1362,22 @@
 }
 
 // Append an (apex, jar) pair to the list.
-func (l *ConfiguredJarList) Append(apex string, jar string) {
-	l.apexes = append(l.apexes, apex)
-	l.jars = append(l.jars, jar)
+func (l *ConfiguredJarList) Append(apex string, jar string) ConfiguredJarList {
+	// Create a copy of the backing arrays before appending to avoid sharing backing
+	// arrays that are mutated across instances.
+	apexes := make([]string, 0, len(l.apexes)+1)
+	copy(apexes, l.apexes)
+	apexes = append(apexes, apex)
+
+	jars := make([]string, 0, len(l.jars)+1)
+	copy(jars, l.jars)
+	jars = append(l.jars, jar)
+
+	return ConfiguredJarList{apexes, jars}
 }
 
 // Filter out sublist.
-func (l *ConfiguredJarList) RemoveList(list ConfiguredJarList) {
+func (l *ConfiguredJarList) RemoveList(list ConfiguredJarList) ConfiguredJarList {
 	apexes := make([]string, 0, l.Len())
 	jars := make([]string, 0, l.Len())
 
@@ -1380,13 +1389,7 @@
 		}
 	}
 
-	l.apexes = apexes
-	l.jars = jars
-}
-
-// A copy of itself.
-func (l *ConfiguredJarList) CopyOf() ConfiguredJarList {
-	return ConfiguredJarList{CopyOf(l.apexes), CopyOf(l.jars)}
+	return ConfiguredJarList{apexes, jars}
 }
 
 // A copy of the list of strings containing jar components.
@@ -1461,17 +1464,16 @@
 }
 
 func CreateConfiguredJarList(ctx PathContext, list []string) ConfiguredJarList {
-	apexes := make([]string, 0, len(list))
-	jars := make([]string, 0, len(list))
+	apexes := make([]string, len(list))
+	jars := make([]string, len(list))
 
-	l := ConfiguredJarList{apexes, jars}
-
-	for _, apexjar := range list {
+	for i, apexjar := range list {
 		apex, jar := splitConfiguredJarPair(ctx, apexjar)
-		l.Append(apex, jar)
+		apexes[i] = apex
+		jars[i] = jar
 	}
 
-	return l
+	return ConfiguredJarList{apexes, jars}
 }
 
 func EmptyConfiguredJarList() ConfiguredJarList {
diff --git a/java/dexpreopt_config.go b/java/dexpreopt_config.go
index 0f8888a..c315124 100644
--- a/java/dexpreopt_config.go
+++ b/java/dexpreopt_config.go
@@ -81,13 +81,12 @@
 		targets := dexpreoptTargets(ctx)
 		deviceDir := android.PathForOutput(ctx, ctx.Config().DeviceName())
 
-		artModules := global.ArtApexJars.CopyOf()
+		artModules := global.ArtApexJars
 		// With EMMA_INSTRUMENT_FRAMEWORK=true the Core libraries depend on jacoco.
 		if ctx.Config().IsEnvTrue("EMMA_INSTRUMENT_FRAMEWORK") {
-			artModules.Append("com.android.art", "jacocoagent")
+			artModules = artModules.Append("com.android.art", "jacocoagent")
 		}
-		frameworkModules := global.BootJars.CopyOf()
-		frameworkModules.RemoveList(artModules)
+		frameworkModules := global.BootJars.RemoveList(artModules)
 
 		artSubdir := "apex/art_boot_images/javalib"
 		frameworkSubdir := "system/framework"