diff --git a/src/java/org/apache/poi/hpsf/Section.java b/src/java/org/apache/poi/hpsf/Section.java
index 2c49f02231..945cdf567c 100644
--- a/src/java/org/apache/poi/hpsf/Section.java
+++ b/src/java/org/apache/poi/hpsf/Section.java
@@ -294,7 +294,7 @@ public class Section
      * <p>Represents an entry in the property list and holds a property's ID and
      * its offset from the section's beginning.</p>
      */
-    class PropertyListEntry implements Comparable<PropertyListEntry>
+    static class PropertyListEntry implements Comparable<PropertyListEntry>
     {
         int id;
         int offset;
diff --git a/src/java/org/apache/poi/ss/util/cellwalk/CellWalk.java b/src/java/org/apache/poi/ss/util/cellwalk/CellWalk.java
index 4efd80d60c..667fb03c53 100644
--- a/src/java/org/apache/poi/ss/util/cellwalk/CellWalk.java
+++ b/src/java/org/apache/poi/ss/util/cellwalk/CellWalk.java
@@ -108,7 +108,7 @@ public class CellWalk {
      *
      * @author Roman Kashitsyn
      */
-    private class SimpleCellWalkContext implements CellWalkContext {
+    private static class SimpleCellWalkContext implements CellWalkContext {
         public long ordinalNumber = 0;
         public int rowNumber = 0;
         public int colNumber = 0;
diff --git a/src/ooxml/java/org/apache/poi/POIXMLProperties.java b/src/ooxml/java/org/apache/poi/POIXMLProperties.java
index 88015a0caf..307b3d8e58 100644
--- a/src/ooxml/java/org/apache/poi/POIXMLProperties.java
+++ b/src/ooxml/java/org/apache/poi/POIXMLProperties.java
@@ -167,7 +167,7 @@ public class POIXMLProperties {
 	/**
 	 * The core document properties
 	 */
-	public class CoreProperties {
+	public static class CoreProperties {
 		private PackagePropertiesPart part;
 		private CoreProperties(PackagePropertiesPart part) {
 			this.part = part;
@@ -273,7 +273,7 @@ public class POIXMLProperties {
 	/**
 	 * Extended document properties
 	 */
-	public class ExtendedProperties {
+	public static class ExtendedProperties {
 		private org.openxmlformats.schemas.officeDocument.x2006.extendedProperties.PropertiesDocument props;
 		private ExtendedProperties(org.openxmlformats.schemas.officeDocument.x2006.extendedProperties.PropertiesDocument props) {
 			this.props = props;
@@ -287,7 +287,7 @@ public class POIXMLProperties {
 	/**
 	 *  Custom document properties
 	 */
-	public class CustomProperties {
+	public static class CustomProperties {
 		/**
 		 *  Each custom property element contains an fmtid attribute
 		 *  with the same GUID value ({D5CDD505-2E9C-101B-9397-08002B2CF9AE}).
diff --git a/src/ooxml/java/org/apache/poi/openxml4j/util/ZipInputStreamZipEntrySource.java b/src/ooxml/java/org/apache/poi/openxml4j/util/ZipInputStreamZipEntrySource.java
index 45674f897e..f7f334c75c 100644
--- a/src/ooxml/java/org/apache/poi/openxml4j/util/ZipInputStreamZipEntrySource.java
+++ b/src/ooxml/java/org/apache/poi/openxml4j/util/ZipInputStreamZipEntrySource.java
@@ -66,6 +66,7 @@ public class ZipInputStreamZipEntrySource implements ZipEntrySource {
 	}
 	
 	public InputStream getInputStream(ZipEntry zipEntry) {
+	    assert (zipEntry instanceof FakeZipEntry);
 		FakeZipEntry entry = (FakeZipEntry)zipEntry;
 		return entry.getInputStream();
 	}
diff --git a/src/scratchpad/src/org/apache/poi/hdgf/chunks/ChunkFactory.java b/src/scratchpad/src/org/apache/poi/hdgf/chunks/ChunkFactory.java
index 1a7c3c6da4..47fa5830d0 100644
--- a/src/scratchpad/src/org/apache/poi/hdgf/chunks/ChunkFactory.java
+++ b/src/scratchpad/src/org/apache/poi/hdgf/chunks/ChunkFactory.java
@@ -187,7 +187,7 @@ public final class ChunkFactory {
 	 * The definition of a Command, which a chunk may hold.
 	 * The Command holds the value, this describes it.
 	 */
-	public class CommandDefinition {
+	public static class CommandDefinition {
 		private int type;
 		private int offset;
 		private String name;
diff --git a/src/scratchpad/src/org/apache/poi/hslf/record/SlideAtom.java b/src/scratchpad/src/org/apache/poi/hslf/record/SlideAtom.java
index 8d697843fc..68f75c09b1 100644
--- a/src/scratchpad/src/org/apache/poi/hslf/record/SlideAtom.java
+++ b/src/scratchpad/src/org/apache/poi/hslf/record/SlideAtom.java
@@ -17,10 +17,11 @@
 
 package org.apache.poi.hslf.record;
 
-import org.apache.poi.util.LittleEndian;
 import java.io.IOException;
 import java.io.OutputStream;
 
+import org.apache.poi.util.LittleEndian;
+
 /**
  * A Slide Atom (type 1007). Holds information on the parent Slide, what
  *  Master Slide it uses, what Notes is attached to it, that sort of thing.
@@ -173,7 +174,7 @@ public final class SlideAtom extends RecordAtom
 	 *  usual record header. Since it's a fixed size and tied to
 	 *  the SlideAtom, we'll hold it here.)
 	 */
-	public class SSlideLayoutAtom {
+	public static class SSlideLayoutAtom {
 		// The different kinds of geometry
 		public static final int TITLE_SLIDE = 0;
 		public static final int TITLE_BODY_SLIDE = 1;
diff --git a/src/scratchpad/src/org/apache/poi/hslf/record/SlideListWithText.java b/src/scratchpad/src/org/apache/poi/hslf/record/SlideListWithText.java
index bb417a6dde..d15944502f 100644
--- a/src/scratchpad/src/org/apache/poi/hslf/record/SlideListWithText.java
+++ b/src/scratchpad/src/org/apache/poi/hslf/record/SlideListWithText.java
@@ -17,12 +17,12 @@
 
 package org.apache.poi.hslf.record;
 
-import org.apache.poi.util.LittleEndian;
-
 import java.io.IOException;
 import java.io.OutputStream;
 import java.util.Vector;
 
+import org.apache.poi.util.LittleEndian;
+
 /**
  * These are tricky beasts. They contain the text of potentially
  *  many (normal) slides. They are made up of several sets of
@@ -181,7 +181,7 @@ public final class SlideListWithText extends RecordContainer {
 	 *  includes sets of TextHeaderAtom and TextBytesAtom/TextCharsAtom,
 	 *  along with some others.
 	 */
-	public class SlideAtomsSet {
+	public static class SlideAtomsSet {
 		private SlidePersistAtom slidePersistAtom;
 		private Record[] slideRecords;