diff --git a/src/lbx_zlib/lbx_zlib.h b/src/lbx_zlib/lbx_zlib.h
index 4e533f3..b990e2f 100644
--- a/src/lbx_zlib/lbx_zlib.h
+++ b/src/lbx_zlib/lbx_zlib.h
@@ -135,9 +135,9 @@ extern int FlushIovBuf ( int fd, struct iovec *iovbuf );
 #endif
 
 /* lbx_zlib.c */
-unsigned long stream_out_compressed;
-unsigned long stream_out_uncompressed;
-unsigned long stream_out_plain;
-unsigned long stream_in_compressed;
-unsigned long stream_in_uncompressed;
-unsigned long stream_in_plain;
+extern unsigned long stream_out_compressed;
+extern unsigned long stream_out_uncompressed;
+extern unsigned long stream_out_plain;
+extern unsigned long stream_in_compressed;
+extern unsigned long stream_in_uncompressed;
+extern unsigned long stream_in_plain;