--- a/src/jdk.internal.vm.compiler/share/classes/org.graalvm.compiler.replacements/src/org/graalvm/compiler/replacements/Log.java	Mon Jun 18 16:13:21 2018 +0200
+++ b/src/jdk.internal.vm.compiler/share/classes/org.graalvm.compiler.replacements/src/org/graalvm/compiler/replacements/Log.java	Mon Jun 18 09:48:22 2018 -0700
@@ -40,7 +40,7 @@
 
     public static final ForeignCallDescriptor LOG_PRIMITIVE = new ForeignCallDescriptor("logPrimitive", void.class, int.class, long.class, boolean.class);
     public static final ForeignCallDescriptor LOG_OBJECT = new ForeignCallDescriptor("logObject", void.class, Object.class, boolean.class, boolean.class);
-    public static final ForeignCallDescriptor LOG_PRINTF = new ForeignCallDescriptor("logPrintf", void.class, Object.class, long.class, long.class, long.class);
+    public static final ForeignCallDescriptor LOG_PRINTF = new ForeignCallDescriptor("logPrintf", void.class, String.class, long.class, long.class, long.class);
 
     @NodeIntrinsic(ForeignCallNode.class)
     private static native void log(@ConstantNodeParameter ForeignCallDescriptor logObject, Object object, boolean asString, boolean newline);