diff --git a/nf2ff/nf2ff.pro b/nf2ff/nf2ff.pro
index bbf99af..9d99f62 100644
--- a/nf2ff/nf2ff.pro
+++ b/nf2ff/nf2ff.pro
@@ -18,6 +18,8 @@ win32 {
     # hdf5
     INCLUDEPATH += $$WIN32_LIB_ROOT/hdf5/include
     LIBS += -L$$WIN32_LIB_ROOT/hdf5/lib -lhdf5
+    # zlib
+    LIBS += -L$$WIN32_LIB_ROOT/zlib/lib -lz
 
     # boost
     DEFINES += BOOST_THREAD_USE_LIB
diff --git a/openEMS.pro b/openEMS.pro
index fd43813..79f1ee7 100644
--- a/openEMS.pro
+++ b/openEMS.pro
@@ -48,6 +48,8 @@ win32 {
     # hdf5
     INCLUDEPATH += $$WIN32_LIB_ROOT/hdf5/include $$WIN32_LIB_ROOT/hdf5/include/cpp
     LIBS += -L$$WIN32_LIB_ROOT/hdf5/lib -lhdf5
+    # zlib
+    LIBS += -L$$WIN32_LIB_ROOT/zlib/lib -lz
     # boost
     DEFINES += BOOST_THREAD_USE_LIB
     INCLUDEPATH += $$WIN32_LIB_ROOT/boost/include