diff --git a/lib/3rdparty/bzip2/CMakeLists.txt b/lib/3rdparty/bzip2/CMakeLists.txt
index a1a943aaee2..ee76113cfc4 100644
--- a/lib/3rdparty/bzip2/CMakeLists.txt
+++ b/lib/3rdparty/bzip2/CMakeLists.txt
@@ -1,7 +1,7 @@
 
 add_definitions(-DBZ_NO_STDIO -DBZ_DECOMPRESS_ONLY)
 
-spec2def(bzip2 unbzip2.spec)
+spec2def(unbzip2.sys unbzip2.spec)
 
 list(APPEND SOURCE
     bzlib.c