diff --git a/src/documentation/content/xdocs/status.xml b/src/documentation/content/xdocs/status.xml
index cea8287434..f8ee55fdde 100644
--- a/src/documentation/content/xdocs/status.xml
+++ b/src/documentation/content/xdocs/status.xml
@@ -34,6 +34,7 @@
 
     <changes>
         <release version="3.7-SNAPSHOT" date="2010-??-??">
+           <action dev="POI-DEVELOPERS" type="fix">48571 - properly close all IO streams created in OPCPackage</action>
            <action dev="POI-DEVELOPERS" type="fix">48572 - always copy all declared inner classes and interfaces when generating poi-ooxml-schemas</action>
            <action dev="POI-DEVELOPERS" type="add">Low Level record support for the ExtRst (phonetic text) part of Unicode Strings. No usermodel access to it as yet though.</action>
            <action dev="POI-DEVELOPERS" type="fix">record.UnicodeString has moved to record.common.UnicodeString, to live with the other record-part classes, as it isn't a full record.</action>
diff --git a/src/ooxml/java/org/apache/poi/openxml4j/opc/OPCPackage.java b/src/ooxml/java/org/apache/poi/openxml4j/opc/OPCPackage.java
index e67055838d..fe2c3e2799 100644
--- a/src/ooxml/java/org/apache/poi/openxml4j/opc/OPCPackage.java
+++ b/src/ooxml/java/org/apache/poi/openxml4j/opc/OPCPackage.java
@@ -367,6 +367,7 @@ public abstract class OPCPackage implements RelationshipSource {
 				}
 			} else if (this.output != null) {
 				save(this.output);
+				output.close();
 			}
 		} finally {
 			l.writeLock().unlock();
@@ -433,8 +434,10 @@ public abstract class OPCPackage implements RelationshipSource {
 				PackageRelationshipTypes.THUMBNAIL);
 
 		// Copy file data to the newly created part
-		StreamHelper.copyStream(new FileInputStream(path), thumbnailPart
+		FileInputStream is = new FileInputStream(path);
+		StreamHelper.copyStream(is, thumbnailPart
 				.getOutputStream());
+		is.close();
 	}
 
 	/**
@@ -1302,6 +1305,7 @@ public abstract class OPCPackage implements RelationshipSource {
 			throw new IOException(e.getLocalizedMessage());
 		}
 		this.save(fos);
+		fos.close();
 	}
 
 	/**