diff --git a/build_3rdparty.py b/build_3rdparty.py
index c217f77..93f8a73 100755
--- a/build_3rdparty.py
+++ b/build_3rdparty.py
@@ -93,6 +93,7 @@
         'target': {
             'mingw-w64': {
                 'result':   ['include/libssh/libssh.h', 'lib/libssh.a'],
+                'replace':  [('src/CMakeLists.txt', 'set_target_properties(ssh PROPERTIES COMPILE_FLAGS "-D_POSIX_SOURCE")', '')],
                 'commands': [
                     'cmake -DCMAKE_SYSTEM_NAME=Windows \
                         -DCMAKE_C_COMPILER=%(prefix)s-gcc -DCMAKE_CXX_COMPILER=%(prefix)s-g++ \
@@ -105,6 +106,7 @@
             },
             'mingw-w64_x64': {
                 'result':   ['include/libssh/libssh.h', 'lib/libssh.a'],
+                'replace':  [('src/CMakeLists.txt', 'set_target_properties(ssh PROPERTIES COMPILE_FLAGS "-D_POSIX_SOURCE")', '')],
                 'commands': [
                     'cmake -DCMAKE_SYSTEM_NAME=Windows \
                         -DCMAKE_C_COMPILER=%(prefix)s-gcc -DCMAKE_CXX_COMPILER=%(prefix)s-g++ \