diff --git a/Foundation/src/DeflatingStream.cpp b/Foundation/src/DeflatingStream.cpp
index 1adb54fb3..56d7b9146 100644
--- a/Foundation/src/DeflatingStream.cpp
+++ b/Foundation/src/DeflatingStream.cpp
@@ -27,13 +27,20 @@ DeflatingStreamBuf::DeflatingStreamBuf(std::istream& istr, StreamType type, int
 	_pOstr(0),
 	_eof(false)
 {
+	_zstr.next_in   = 0;
+	_zstr.avail_in  = 0;
+	_zstr.total_in  = 0;
+	_zstr.next_out  = 0;
+	_zstr.avail_out = 0;
+	_zstr.total_out = 0;
+	_zstr.msg       = 0;
+	_zstr.state     = 0;
 	_zstr.zalloc    = Z_NULL;
 	_zstr.zfree     = Z_NULL;
 	_zstr.opaque    = Z_NULL;
-	_zstr.next_in   = 0;
-	_zstr.avail_in  = 0;
-	_zstr.next_out  = 0;
-	_zstr.avail_out = 0;
+	_zstr.data_type = 0;
+	_zstr.adler     = 0;
+	_zstr.reserved  = 0;
 
 	_buffer = new char[DEFLATE_BUFFER_SIZE];
 
diff --git a/Foundation/src/InflatingStream.cpp b/Foundation/src/InflatingStream.cpp
index 77ecb500b..1eac3fa1a 100644
--- a/Foundation/src/InflatingStream.cpp
+++ b/Foundation/src/InflatingStream.cpp
@@ -16,6 +16,7 @@
 
 #include "Poco/InflatingStream.h"
 #include "Poco/Exception.h"
+#include <cstring>
 
 
 namespace Poco {
@@ -28,13 +29,20 @@ InflatingStreamBuf::InflatingStreamBuf(std::istream& istr, StreamType type):
 	_eof(false),
 	_check(type != STREAM_ZIP)
 {
+	_zstr.next_in   = 0;
+	_zstr.avail_in  = 0;
+	_zstr.total_in  = 0;
+	_zstr.next_out  = 0;
+	_zstr.avail_out = 0;
+	_zstr.total_out = 0;
+	_zstr.msg       = 0;
+	_zstr.state     = 0;
 	_zstr.zalloc    = Z_NULL;
 	_zstr.zfree     = Z_NULL;
 	_zstr.opaque    = Z_NULL;
-	_zstr.next_in   = 0;
-	_zstr.avail_in  = 0;
-	_zstr.next_out  = 0;
-	_zstr.avail_out = 0;
+	_zstr.data_type = 0;
+	_zstr.adler     = 0;
+	_zstr.reserved  = 0;
 
 	_buffer = new char[INFLATE_BUFFER_SIZE];