diff -r -u a/FreeFileSync/Source/Makefile b/FreeFileSync/Source/Makefile
--- a/FreeFileSync/Source/Makefile
+++ b/FreeFileSync/Source/Makefile
@@ -4,7 +4,7 @@
            -Wall -Wfatal-errors -Wmissing-include-dirs -Wswitch-enum -Wcast-align -Wshadow -Wnon-virtual-dtor \
            -O3 -DNDEBUG `wx-config --cxxflags --debug=no` -pthread
 
-linkFlags = -s -no-pie `wx-config --libs std, aui, richtext --debug=no` -pthread
+linkFlags = -s -no-pie `wx-config --libs std, aui, richtext  --debug=no` -lz -pthread
 
 
 cxxFlags  += `pkg-config --cflags openssl`
@@ -17,6 +17,7 @@
 linkFlags += `pkg-config --libs   libssh2`
 
 cxxFlags  += `pkg-config --cflags gtk+-2.0`
+linkFlags += `pkg-config --libs   gtk+-2.0`
 #treat as system headers so that warnings are hidden:
 cxxFlags  += -isystem/usr/include/gtk-2.0

diff -r -u a/FreeFileSync/Source/RealTimeSync/Makefile b/FreeFileSync/Source/RealTimeSync/Makefile
--- a/FreeFileSync/Source/RealTimeSync/Makefile
+++ b/FreeFileSync/Source/RealTimeSync/Makefile
@@ -4,10 +4,11 @@
            -Wall -Wfatal-errors -Wmissing-include-dirs -Wswitch-enum -Wcast-align -Wshadow -Wnon-virtual-dtor \
            -O3 -DNDEBUG `wx-config --cxxflags --debug=no` -pthread
 
-linkFlags = -s -no-pie `wx-config --libs std, aui, richtext --debug=no` -pthread
+linkFlags = -s -no-pie `wx-config --libs std, aui, richtext  --debug=no` -lz -pthread
 
 #Gtk - support "no button border"
 cxxFlags  += `pkg-config --cflags gtk+-2.0`
+linkFlags += `pkg-config --libs   gtk+-2.0`
 #treat as system headers so that warnings are hidden:
 cxxFlags  += -isystem/usr/include/gtk-2.0