diff --git a/.classpath b/.classpath
index 04c931991..bfe9ee244 100644
--- a/.classpath
+++ b/.classpath
@@ -35,5 +35,6 @@
 	<classpathentry exported="true" kind="lib" path="lib/commons-logging-1.2.jar"/>
 	<classpathentry exported="true" kind="lib" path="lib/commons-collections4-4.1.jar"/>
 	<classpathentry kind="lib" path="lib/commons-math3-3.6.1.jar"/>
+	<classpathentry kind="lib" path="lib/mockito-core-2.13.0.jar"/>
 	<classpathentry kind="output" path="bin"/>
 </classpath>
diff --git a/build.gradle b/build.gradle
index e209e7a54..cf32c436f 100644
--- a/build.gradle
+++ b/build.gradle
@@ -211,6 +211,7 @@ project('ooxml') {
 		compile files('../../ooxml-lib/ooxml-security-1.1.jar')
 		
 		testCompile 'junit:junit:4.12'
+		testCompile 'org.mockito:mockito-core:2.13.0'
 		testCompile project(path: ':main', configuration: 'tests')
 		testCompile 'org.openjdk.jmh:jmh-core:1.19'
 		testCompile 'org.openjdk.jmh:jmh-generator-annprocess:1.19'
diff --git a/build.xml b/build.xml
index 10462ee1e..8a4dc2531 100644
--- a/build.xml
+++ b/build.xml
@@ -164,6 +164,8 @@ under the License.
 
     <property name="main.hamcrest.jar" location="${main.lib}/hamcrest-core-1.3.jar"/>
     <property name="main.hamcrest.url" value="${repository.m2}/maven2/org/hamcrest/hamcrest-core/1.3/hamcrest-core-1.3.jar"/>
+    <property name="main.mockito.jar" location="${main.lib}/mockito-core-2.13.0.jar"/>
+    <property name="main.mockito.url" value="${repository.m2}/maven2/org/mockito/mockito-core/2.13.0/mockito-core-2.13.0.jar"/>
     <property name="main.ant.jar" location="${main.lib}/ant-1.10.1.jar"/>
     <property name="main.ant.url" value="${repository.m2}/maven2/org/apache/ant/ant/1.10.1/ant-1.10.1.jar"/>
     <property name="main.antlauncher.jar" location="${main.lib}/ant-launcher-1.10.1.jar"/>
@@ -317,6 +319,7 @@ under the License.
         <pathelement location="${main.jmh.jar}"/>
         <pathelement location="${main.jmhAnnotation.jar}"/>
         <pathelement location="${main.hamcrest.jar}"/>
+        <pathelement location="${main.mockito.jar}"/>
     </path>
 
     <path id="scratchpad.classpath">
@@ -620,6 +623,7 @@ under the License.
                     <available file="${main.jmh.jar}"/>
                     <available file="${main.jmhAnnotation.jar}"/>
                     <available file="${main.hamcrest.jar}"/>
+                    <available file="${main.mockito.jar}"/>
                     <available file="${main.ant.jar}"/>
                     <available file="${main.antlauncher.jar}"/>
                     <available file="${asm.jar}"/>
@@ -651,6 +655,7 @@ under the License.
         <downloadfile src="${main.jmh.url}" dest="${main.jmh.jar}"/>
         <downloadfile src="${main.jmhAnnotation.url}" dest="${main.jmhAnnotation.jar}"/>
         <downloadfile src="${main.hamcrest.url}" dest="${main.hamcrest.jar}"/>
+        <downloadfile src="${main.mockito.url}" dest="${main.mockito.jar}"/>
         <downloadfile src="${main.ant.url}" dest="${main.ant.jar}"/>
         <downloadfile src="${main.antlauncher.url}" dest="${main.antlauncher.jar}"/>
         <downloadfile src="${asm.url}" dest="${asm.jar}"/>
diff --git a/gradle/wrapper/gradle-wrapper.jar b/gradle/wrapper/gradle-wrapper.jar
index 314d6ec1b..849557c7e 100644
Binary files a/gradle/wrapper/gradle-wrapper.jar and b/gradle/wrapper/gradle-wrapper.jar differ
diff --git a/src/ooxml/testcases/org/apache/poi/xslf/usermodel/TestXSLFTextRun.java b/src/ooxml/testcases/org/apache/poi/xslf/usermodel/TestXSLFTextRun.java
index 1640d499e..9c0c1b6b5 100644
--- a/src/ooxml/testcases/org/apache/poi/xslf/usermodel/TestXSLFTextRun.java
+++ b/src/ooxml/testcases/org/apache/poi/xslf/usermodel/TestXSLFTextRun.java
@@ -22,6 +22,8 @@ import static org.apache.poi.sl.TestCommonSL.sameColor;
 import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertFalse;
 import static org.junit.Assert.assertTrue;
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.when;
 
 import java.awt.Color;
 import java.io.IOException;
@@ -96,4 +98,17 @@ public class TestXSLFTextRun {
             assertEquals(unicodeSurrogates, r.getRenderableText(unicodeSurrogates));
         }
     }
+
+    @Test
+    public void testCopyNullFontSize() throws IOException {
+        XMLSlideShow ppt = new XMLSlideShow();
+        XSLFSlide slide = ppt.createSlide();
+        XSLFTextShape sh = slide.createAutoShape();
+
+        XSLFTextRun r = sh.addNewTextParagraph().addNewTextRun();
+        XSLFTextRun s = mock(XSLFTextRun.class);
+        when(s.getFontSize()).thenReturn(null);
+
+        r.copy(s);
+    }
 }