diff --git a/src/main/java/com/android/tools/r8/Version.java b/src/main/java/com/android/tools/r8/Version.java
index 00b3cce..5344a61 100644
--- a/src/main/java/com/android/tools/r8/Version.java
+++ b/src/main/java/com/android/tools/r8/Version.java
@@ -11,7 +11,7 @@
 
   // This field is accessed from release scripts using simple pattern matching.
   // Therefore, changing this field could break our release scripts.
-  public static final String LABEL = "v1.0.0";
+  public static final String LABEL = "v1.0.1";
 
   private Version() {
   }
diff --git a/src/main/java/com/android/tools/r8/shaking/RootSetBuilder.java b/src/main/java/com/android/tools/r8/shaking/RootSetBuilder.java
index c46b1a2..f504930 100644
--- a/src/main/java/com/android/tools/r8/shaking/RootSetBuilder.java
+++ b/src/main/java/com/android/tools/r8/shaking/RootSetBuilder.java
@@ -40,6 +40,7 @@
 import java.util.Map;
 import java.util.Map.Entry;
 import java.util.Set;
+import java.util.concurrent.ConcurrentHashMap;
 import java.util.concurrent.ExecutionException;
 import java.util.concurrent.ExecutorService;
 import java.util.concurrent.Future;
@@ -396,17 +397,12 @@
     return false;
   }
 
-  private final IdentityHashMap<DexString, String> stringCache = new IdentityHashMap<>();
-  private final IdentityHashMap<DexType, String> typeCache = new IdentityHashMap<>();
+  private final ConcurrentHashMap<DexString, String> stringCache = new ConcurrentHashMap<>();
 
   public String lookupString(DexString name) {
     return stringCache.computeIfAbsent(name, DexString::toString);
   }
 
-  public String lookupType(DexType type) {
-    return typeCache.computeIfAbsent(type, DexType::toSourceString);
-  }
-
   private void markMethod(DexEncodedMethod method, Collection<ProguardMemberRule> rules,
       ProguardConfigurationRule context, Set<Wrapper<DexMethod>> methodsMarked,
       DexType onlyIfClassKept) {