diff --git a/modules/lang-painless/src/main/java/org/elasticsearch/painless/Def.java b/modules/lang-painless/src/main/java/org/elasticsearch/painless/Def.java
index 102441effb1..c18b724c350 100644
--- a/modules/lang-painless/src/main/java/org/elasticsearch/painless/Def.java
+++ b/modules/lang-painless/src/main/java/org/elasticsearch/painless/Def.java
@@ -29,7 +29,6 @@ import java.lang.invoke.MethodHandle;
 import java.lang.invoke.MethodHandles;
 import java.lang.invoke.MethodHandles.Lookup;
 import java.lang.invoke.MethodType;
-import java.util.Arrays;
 import java.util.Collections;
 import java.util.Iterator;
 import java.util.List;
@@ -321,14 +320,26 @@ public final class Def {
                                                          String call, Class<?>... captures) throws LambdaConversionException {
          final FunctionRef ref;
          if ("this".equals(type)) {
+             // user written method
              Method interfaceMethod = clazz.struct.getFunctionalMethod();
              if (interfaceMethod == null) {
                  throw new IllegalArgumentException("Cannot convert function reference [" + type + "::" + call + "] " +
                                                     "to [" + clazz.name + "], not a functional interface");
              }
-             int arity = interfaceMethod.arguments.size();
-             // user written method
-             ref = null;
+             int arity = interfaceMethod.arguments.size() + captures.length;
+             final MethodHandle handle;
+             try {
+                 MethodHandle accessor = lookup.findStaticGetter(lookup.lookupClass(), 
+                                                                 "handle$" + call + "$" + arity, 
+                                                                 MethodHandle.class);
+                 handle = (MethodHandle) accessor.invokeExact();
+             } catch (NoSuchFieldException | IllegalAccessException e) {
+                 throw new IllegalArgumentException("Unknown call [" + call + "] with [" + arity + "] arguments.");
+             } catch (Throwable t) {
+                 rethrow(t);
+                 throw new AssertionError();
+             }
+             ref = new FunctionRef(clazz, interfaceMethod, handle, captures);
          } else {
              // whitelist lookup
              ref = new FunctionRef(clazz, type, call, captures);
diff --git a/modules/lang-painless/src/main/java/org/elasticsearch/painless/FunctionRef.java b/modules/lang-painless/src/main/java/org/elasticsearch/painless/FunctionRef.java
index 7e0fd520b75..9015b4dee61 100644
--- a/modules/lang-painless/src/main/java/org/elasticsearch/painless/FunctionRef.java
+++ b/modules/lang-painless/src/main/java/org/elasticsearch/painless/FunctionRef.java
@@ -101,6 +101,27 @@ public class FunctionRef {
         samMethodType = impl.getMethodType().dropParameterTypes(0, captures.length);
     }
 
+    /**
+     * Creates a new FunctionRef (low level). 
+     * <p>
+     * This will <b>not</b> set implMethodASM. It is for runtime use only.
+     */
+    public FunctionRef(Definition.Type expected, Definition.Method method, MethodHandle impl, Class<?>... captures) {
+        // e.g. compareTo
+        invokedName = method.name;
+        // e.g. (Object)Comparator
+        invokedType = MethodType.methodType(expected.clazz, captures);
+        // e.g. (Object,Object)int
+        interfaceMethodType = method.getMethodType().dropParameterTypes(0, 1);
+
+        implMethod = impl;
+        
+        implMethodASM = null;
+        
+        // remove any prepended captured arguments for the 'natural' signature.
+        samMethodType = impl.type().dropParameterTypes(0, captures.length);
+    }
+
     /** 
      * Looks up {@code type::call} from the whitelist, and returns a matching method.
      */
diff --git a/modules/lang-painless/src/main/java/org/elasticsearch/painless/node/EFunctionRef.java b/modules/lang-painless/src/main/java/org/elasticsearch/painless/node/EFunctionRef.java
index 30b4fc37901..00a69e0b7b9 100644
--- a/modules/lang-painless/src/main/java/org/elasticsearch/painless/node/EFunctionRef.java
+++ b/modules/lang-painless/src/main/java/org/elasticsearch/painless/node/EFunctionRef.java
@@ -31,7 +31,6 @@ import org.objectweb.asm.Type;
 import static org.elasticsearch.painless.WriterConstants.LAMBDA_BOOTSTRAP_HANDLE;
 
 import java.lang.invoke.LambdaMetafactory;
-import java.lang.reflect.Modifier;
 
 /**
  * Represents a function reference.
diff --git a/modules/lang-painless/src/test/java/org/elasticsearch/painless/FunctionRefTests.java b/modules/lang-painless/src/test/java/org/elasticsearch/painless/FunctionRefTests.java
index 8790ba61e40..00e52f056d9 100644
--- a/modules/lang-painless/src/test/java/org/elasticsearch/painless/FunctionRefTests.java
+++ b/modules/lang-painless/src/test/java/org/elasticsearch/painless/FunctionRefTests.java
@@ -114,7 +114,6 @@ public class FunctionRefTests extends ScriptTestCase {
                              "List l = new ArrayList(); l.add(2); l.add(1); l.sort(this::mycompare); return l.get(0);"));
     }
     
-    @AwaitsFix(bugUrl = "working on it")
     public void testOwnStaticMethodReferenceDef() {
         assertEquals(2, exec("int mycompare(int i, int j) { j - i } " +
                              "def l = new ArrayList(); l.add(2); l.add(1); l.sort(this::mycompare); return l.get(0);"));