diff --git a/core/src/main/java/org/bitcoinj/store/SPVBlockStore.java b/core/src/main/java/org/bitcoinj/store/SPVBlockStore.java
index 3d28efed..ba216c6c 100644
--- a/core/src/main/java/org/bitcoinj/store/SPVBlockStore.java
+++ b/core/src/main/java/org/bitcoinj/store/SPVBlockStore.java
@@ -20,6 +20,8 @@ import org.bitcoinj.core.*;
 import org.bitcoinj.utils.*;
 import org.slf4j.*;
 
+import com.google.common.base.Charsets;
+
 import javax.annotation.*;
 import java.io.*;
 import java.nio.*;
@@ -131,7 +133,7 @@ public class SPVBlockStore implements BlockStore {
             if (exists) {
                 header = new byte[4];
                 buffer.get(header);
-                if (!new String(header, "US-ASCII").equals(HEADER_MAGIC))
+                if (!new String(header, Charsets.US_ASCII).equals(HEADER_MAGIC))
                     throw new BlockStoreException("Header bytes do not equal " + HEADER_MAGIC);
             } else {
                 initNewStore(params);