diff --git a/java/src/com/google/template/soy/internal/proto/ProtoUtils.java b/java/src/com/google/template/soy/internal/proto/ProtoUtils.java
index 150beb1552..f9ff68cf99 100644
--- a/java/src/com/google/template/soy/internal/proto/ProtoUtils.java
+++ b/java/src/com/google/template/soy/internal/proto/ProtoUtils.java
@@ -18,6 +18,7 @@
 
 import static com.google.common.base.Preconditions.checkArgument;
 
+import com.google.apps.jspb.Jspb;
 import com.google.common.base.CaseFormat;
 import com.google.common.collect.ImmutableSet;
 import com.google.common.collect.Sets;
@@ -239,4 +240,14 @@ public static boolean isMessageLike(FieldDescriptor field) {
     }
     return field.getJavaType() == FieldDescriptor.JavaType.MESSAGE;
   }
+
+  public static boolean isNumberInt64(FieldDescriptor field) {
+    if (field.getJavaType() != FieldDescriptor.JavaType.LONG) {
+      return false;
+    }
+    if (field.getOptions().hasExtension(Jspb.jstype)) {
+      return field.getOptions().getExtension(Jspb.jstype) != Jspb.JsType.STRING;
+    }
+    return field.getOptions().getJstype() != JSType.JS_STRING;
+  }
 }