diff --git a/build.gradle b/build.gradle
index 99b2d2a..b1cb8bb 100644
--- a/build.gradle
+++ b/build.gradle
@@ -7,7 +7,7 @@ buildscript {
   }
   dependencies {
     //Check for the latest version here: http://plugins.gradle.org/plugin/com.jfrog.artifactory
-    classpath 'org.jfrog.buildinfo:build-info-extractor-gradle:4.2.0'
+    classpath 'org.jfrog.buildinfo:build-info-extractor-gradle:4.5.4'
   }
 }
 
@@ -36,8 +36,8 @@ ext {
   hktBaseVersion = '0.9.3'
   hktVersion = hktBaseVersion + (isSnapshot ? '-SNAPSHOT' : '')
 
-  derive4jVersion = '0.10.2'
-  autoService = 'com.google.auto.service:auto-service:1.0-rc2'
+  derive4jVersion = '0.12.3'
+  autoService = 'com.google.auto.service:auto-service:1.0-rc4'
 }
 
 
@@ -50,6 +50,8 @@ dependencies {
 
   compile files(Jvm.current().toolsJar)
 
+  compile 'io.kindedj:kindedj:1.0.1'
+
   compileOnly "org.derive4j:derive4j-annotation:${derive4jVersion}"
   compileOnly autoService
 
@@ -57,7 +59,7 @@ dependencies {
   apt autoService
 
   testCompile 'junit:junit:4.12'
-  testCompile 'com.google.testing.compile:compile-testing:0.8'
+  testCompile 'com.google.testing.compile:compile-testing:0.14'
   testApt rootProject
 }
 
diff --git a/gradle/wrapper/gradle-wrapper.jar b/gradle/wrapper/gradle-wrapper.jar
index 2c6137b..01b8bf6 100644
Binary files a/gradle/wrapper/gradle-wrapper.jar and b/gradle/wrapper/gradle-wrapper.jar differ
diff --git a/gradle/wrapper/gradle-wrapper.properties b/gradle/wrapper/gradle-wrapper.properties
index 889644b..933b647 100644
--- a/gradle/wrapper/gradle-wrapper.properties
+++ b/gradle/wrapper/gradle-wrapper.properties
@@ -1,6 +1,5 @@
-#Wed May 04 21:04:30 CEST 2016
 distributionBase=GRADLE_USER_HOME
 distributionPath=wrapper/dists
 zipStoreBase=GRADLE_USER_HOME
 zipStorePath=wrapper/dists
-distributionUrl=https\://services.gradle.org/distributions/gradle-2.12-all.zip
+distributionUrl=https\://services.gradle.org/distributions/gradle-4.4-bin.zip
diff --git a/gradlew b/gradlew
index 9d82f78..cccdd3d 100755
--- a/gradlew
+++ b/gradlew
@@ -1,4 +1,4 @@
-#!/usr/bin/env bash
+#!/usr/bin/env sh
 
 ##############################################################################
 ##
@@ -6,20 +6,38 @@
 ##
 ##############################################################################
 
-# Add default JVM options here. You can also use JAVA_OPTS and GRADLE_OPTS to pass JVM options to this script.
-DEFAULT_JVM_OPTS=""
+# Attempt to set APP_HOME
+# Resolve links: $0 may be a link
+PRG="$0"
+# Need this for relative symlinks.
+while [ -h "$PRG" ] ; do
+    ls=`ls -ld "$PRG"`
+    link=`expr "$ls" : '.*-> \(.*\)$'`
+    if expr "$link" : '/.*' > /dev/null; then
+        PRG="$link"
+    else
+        PRG=`dirname "$PRG"`"/$link"
+    fi
+done
+SAVED="`pwd`"
+cd "`dirname \"$PRG\"`/" >/dev/null
+APP_HOME="`pwd -P`"
+cd "$SAVED" >/dev/null
 
 APP_NAME="Gradle"
 APP_BASE_NAME=`basename "$0"`
 
+# Add default JVM options here. You can also use JAVA_OPTS and GRADLE_OPTS to pass JVM options to this script.
+DEFAULT_JVM_OPTS=""
+
 # Use the maximum available, or set MAX_FD != -1 to use that value.
 MAX_FD="maximum"
 
-warn ( ) {
+warn () {
     echo "$*"
 }
 
-die ( ) {
+die () {
     echo
     echo "$*"
     echo
@@ -30,6 +48,7 @@ die ( ) {
 cygwin=false
 msys=false
 darwin=false
+nonstop=false
 case "`uname`" in
   CYGWIN* )
     cygwin=true
@@ -40,26 +59,11 @@ case "`uname`" in
   MINGW* )
     msys=true
     ;;
+  NONSTOP* )
+    nonstop=true
+    ;;
 esac
 
-# Attempt to set APP_HOME
-# Resolve links: $0 may be a link
-PRG="$0"
-# Need this for relative symlinks.
-while [ -h "$PRG" ] ; do
-    ls=`ls -ld "$PRG"`
-    link=`expr "$ls" : '.*-> \(.*\)$'`
-    if expr "$link" : '/.*' > /dev/null; then
-        PRG="$link"
-    else
-        PRG=`dirname "$PRG"`"/$link"
-    fi
-done
-SAVED="`pwd`"
-cd "`dirname \"$PRG\"`/" >/dev/null
-APP_HOME="`pwd -P`"
-cd "$SAVED" >/dev/null
-
 CLASSPATH=$APP_HOME/gradle/wrapper/gradle-wrapper.jar
 
 # Determine the Java command to use to start the JVM.
@@ -85,7 +89,7 @@ location of your Java installation."
 fi
 
 # Increase the maximum file descriptors if we can.
-if [ "$cygwin" = "false" -a "$darwin" = "false" ] ; then
+if [ "$cygwin" = "false" -a "$darwin" = "false" -a "$nonstop" = "false" ] ; then
     MAX_FD_LIMIT=`ulimit -H -n`
     if [ $? -eq 0 ] ; then
         if [ "$MAX_FD" = "maximum" -o "$MAX_FD" = "max" ] ; then
@@ -150,11 +154,19 @@ if $cygwin ; then
     esac
 fi
 
-# Split up the JVM_OPTS And GRADLE_OPTS values into an array, following the shell quoting and substitution rules
-function splitJvmOpts() {
-    JVM_OPTS=("$@")
+# Escape application args
+save () {
+    for i do printf %s\\n "$i" | sed "s/'/'\\\\''/g;1s/^/'/;\$s/\$/' \\\\/" ; done
+    echo " "
 }
-eval splitJvmOpts $DEFAULT_JVM_OPTS $JAVA_OPTS $GRADLE_OPTS
-JVM_OPTS[${#JVM_OPTS[*]}]="-Dorg.gradle.appname=$APP_BASE_NAME"
+APP_ARGS=$(save "$@")
+
+# Collect all arguments for the java command, following the shell quoting and substitution rules
+eval set -- $DEFAULT_JVM_OPTS $JAVA_OPTS $GRADLE_OPTS "\"-Dorg.gradle.appname=$APP_BASE_NAME\"" -classpath "\"$CLASSPATH\"" org.gradle.wrapper.GradleWrapperMain "$APP_ARGS"
+
+# by default we should be in the correct project dir, but when run from Finder on Mac, the cwd is wrong
+if [ "$(uname)" = "Darwin" ] && [ "$HOME" = "$PWD" ]; then
+  cd "$(dirname "$0")"
+fi
 
-exec "$JAVACMD" "${JVM_OPTS[@]}" -classpath "$CLASSPATH" org.gradle.wrapper.GradleWrapperMain "$@"
+exec "$JAVACMD" "$@"
diff --git a/gradlew.bat b/gradlew.bat
index 72d362d..e95643d 100644
--- a/gradlew.bat
+++ b/gradlew.bat
@@ -8,14 +8,14 @@
 @rem Set local scope for the variables with windows NT shell
 if "%OS%"=="Windows_NT" setlocal
 
-@rem Add default JVM options here. You can also use JAVA_OPTS and GRADLE_OPTS to pass JVM options to this script.
-set DEFAULT_JVM_OPTS=
-
 set DIRNAME=%~dp0
 if "%DIRNAME%" == "" set DIRNAME=.
 set APP_BASE_NAME=%~n0
 set APP_HOME=%DIRNAME%
 
+@rem Add default JVM options here. You can also use JAVA_OPTS and GRADLE_OPTS to pass JVM options to this script.
+set DEFAULT_JVM_OPTS=
+
 @rem Find java.exe
 if defined JAVA_HOME goto findJavaFromJavaHome
 
@@ -49,7 +49,6 @@ goto fail
 @rem Get command-line arguments, handling Windows variants
 
 if not "%OS%" == "Windows_NT" goto win9xME_args
-if "%@eval[2+2]" == "4" goto 4NT_args
 
 :win9xME_args
 @rem Slurp the command line arguments.
@@ -60,11 +59,6 @@ set _SKIP=2
 if "x%~1" == "x" goto execute
 
 set CMD_LINE_ARGS=%*
-goto execute
-
-:4NT_args
-@rem Get arguments from the 4NT Shell from JP Software
-set CMD_LINE_ARGS=%$
 
 :execute
 @rem Setup the command line
diff --git a/src/main/java/org/derive4j/hkt/__.java b/src/main/java/org/derive4j/hkt/__.java
index 4ce32d6..a3d1c1c 100644
--- a/src/main/java/org/derive4j/hkt/__.java
+++ b/src/main/java/org/derive4j/hkt/__.java
@@ -1,8 +1,10 @@
 package org.derive4j.hkt;
 
+import io.kindedj.Hk;
+
 /**
  * Represents a higher order type (or higher kinded type or type constructor) of arity 1
  * @param <f> the 'witness' of the class/interface to be lifted as type constructor: a static nested class or enum, or the class applied with wildcard type arguments.
  * @param <T> the type parameter of the type constructor
  */
-public interface __<f, T> {}
+public interface __<f, T> extends Hk<f, T> {}
diff --git a/src/main/java/org/derive4j/hkt/processor/GenCode.java b/src/main/java/org/derive4j/hkt/processor/GenCode.java
index 2d61391..5e7294b 100644
--- a/src/main/java/org/derive4j/hkt/processor/GenCode.java
+++ b/src/main/java/org/derive4j/hkt/processor/GenCode.java
@@ -47,7 +47,9 @@ String prefix() {
     }
     private static final String CLASS_TEMPLATE = "package {0};\n" +
         "\n" +
-        "import org.derive4j.hkt.*;\n" +
+        "import org.derive4j.hkt.__;\n" +
+        "import org.derive4j.hkt.TypeEq;\n" +
+        "import io.kindedj.Hk;\n" +
         "{3}\n"+
         "\n" +
         "{1}final class {2} '{'\n" +
@@ -56,13 +58,13 @@ String prefix() {
         "{4}\n" +
         "}";
 
-    private static final String METHODS_TEMPLATE = "  {0}static {2} {1} " +
-        "{4}({3} hkt) '{'\n" +
+    private static final String METHODS_TEMPLATE = "  @SuppressWarnings(\"unchecked\")\n" +
+        "  {0}static {2} {1} {5}({3} hkt) '{'\n" +
         "    return ({1}) hkt;\n" +
         "  }\n" +
         "\n" +
         "  @SuppressWarnings(\"unchecked\")\n" +
-        "  {0}static {2} TypeEq<{3}, {1}> {5}()'{'\n" +
+        "  {0}static {2} TypeEq<{4}, {1}> {6}()'{'\n" +
         "    return (TypeEq) TypeEq.refl();\n" +
         "  }";
 
@@ -215,14 +217,21 @@ private P2<HktEffectiveVisibility, String> genCoerceMethod(TypeElement typeConst
 
         CharSequence typeParams = MessageFormat.format(TYPE_PARAMS_TEMPLATE, showTypeParams(typeConstructor));
 
+        String hkInterfaceFQN = Visitors.asTypeElement.visit(hktInterface.asElement()).get().getQualifiedName().toString();
+
+        String kindedJInterfaceAsString = hktInterface.toString()
+            .replace("<" + hkInterfaceFQN, "<? extends Hk")
+            .replace(hkInterfaceFQN, "Hk")
+            .replace(packageRelativeTypeElement.getQualifiedName(), packageRelativeTypeElement.getSimpleName());
+
         String hktInterfaceAsString = hktInterface.toString()
-            .replace(Visitors.asTypeElement.visit(hktInterface.asElement()).get().getQualifiedName(), hktInterface
-                .asElement().getSimpleName())
+            .replace(hkInterfaceFQN, hktInterface.asElement().getSimpleName())
+            .replace("io.kindedj.Hk", "Hk")
             .replace(packageRelativeTypeElement.getQualifiedName(), packageRelativeTypeElement.getSimpleName());
 
         return _P2.of(visibility,
             MessageFormat.format(METHODS_TEMPLATE, visibility.prefix(), typeAsString, typeParams,
-                hktInterfaceAsString, coerceMethodName, typeEqMethodName));
+                kindedJInterfaceAsString, hktInterfaceAsString, coerceMethodName, typeEqMethodName));
     }
 
     private TypeElement packageRelativeTypeElement(TypeElement typeElement) {