diff --git a/src/klayout.pri b/src/klayout.pri
index dc4eb19b5..02781de7b 100644
--- a/src/klayout.pri
+++ b/src/klayout.pri
@@ -40,18 +40,37 @@ equals(HAVE_64BIT_COORD, "1") {
 }
 
 equals(HAVE_PYTHON, "1") {
+  !isEmpty(BITS_PATH) {
+    include($$BITS_PATH/python/python.pri)
+  }
   DEFINES += HAVE_PYTHON
 }
 
 equals(HAVE_CURL, "1") {
+  !isEmpty(BITS_PATH) {
+    include($$BITS_PATH/curl/curl.pri)
+  } else {
+    LIBS += -lcurl
+    win32 {
+      LIBS += -lwsock32    # required because we do "select"
+    }
+  }
   DEFINES += HAVE_CURL
 }
 
 equals(HAVE_EXPAT, "1") {
+  !isEmpty(BITS_PATH) {
+    include($$BITS_PATH/expat/expat.pri)
+  } else {
+    LIBS += -lexpat
+  }
   DEFINES += HAVE_EXPAT
 }
 
 equals(HAVE_RUBY, "1") {
+  !isEmpty(BITS_PATH) {
+    include($$BITS_PATH/ruby/ruby.pri)
+  }
   DEFINES += \
     HAVE_RUBY \
     HAVE_RUBY_VERSION_CODE=$$RUBYVERSIONCODE 
@@ -61,18 +80,24 @@ equals(HAVE_RUBY, "1") {
   QMAKE_RPATHDIR += $$RPATH
 }
 
+!isEmpty(BITS_PATH) {
+  include($$BITS_PATH/zlib/zlib.pri)
+} else {
+  !msvc {
+    LIBS += -lz
+  }
+}
+
 msvc {
 
-  INCLUDEPATH += \
-    $$THIRD_PARTY/zlib/1.2.11/include \
-
-  QMAKE_CXXFLAGS += -bigobj
+  QMAKE_CXXFLAGS += \
+      /bigobj \
+      /wd4251 \                   # Disable "DLL interface required"
+      /source-charset:utf-8 \     # Use UTF-8 for source files
 
   QMAKE_CXXFLAGS_WARN_ON += \
 
-}
-
-!msvc {
+} else {
 
   QMAKE_CXXFLAGS_WARN_ON += \
       -pedantic \
@@ -85,17 +110,12 @@ msvc {
       -Wno-deprecated-declarations \
       -Wno-reserved-user-defined-literal \
 
-} else {
-
-  QMAKE_CXXFLAGS += \
-      /wd4251 \                   # Disable "DLL interface required"
-      /source-charset:utf-8 \     # Use UTF-8 for source files
-
 }
 
 equals(HAVE_QT, "0") {
 
   QT =
+  LIBS += -lpthread
 
 } else {
 
diff --git a/src/pymod/bridge_sample/bridge_sample.pro b/src/pymod/bridge_sample/bridge_sample.pro
index d9365d455..1e1f58527 100644
--- a/src/pymod/bridge_sample/bridge_sample.pro
+++ b/src/pymod/bridge_sample/bridge_sample.pro
@@ -56,6 +56,10 @@ equals(HAVE_QT, "0") {
 # - GSI (generic scripting interface)
 # - TL (basic toolkit)
 # - PYA (Python binding for GSI)
+!isEmpty(BITS_PATH) {
+  # pull the definitions from the BITS_PATH if set
+  include($$BITS_PATH/python/python.pri)
+}
 INCLUDEPATH += "$$PYTHONINCLUDE" $$INC/tl/tl $$INC/pya/pya $$INC/gsi/gsi
 DEPENDPATH += "$$PYTHONINCLUDE" $$INC/tl/tl $$INC/pya/pya $$INC/gsi/gsi
 LIBS += "$$PYTHONLIBFILE" -L$$LIBDIR -lklayout_tl -lklayout_pya -lklayout_gsi
diff --git a/src/tl/tl/tl.pro b/src/tl/tl/tl.pro
index c796f7e9a..8d57c1b34 100644
--- a/src/tl/tl/tl.pro
+++ b/src/tl/tl/tl.pro
@@ -6,32 +6,6 @@ include($$PWD/../../lib.pri)
 
 DEFINES += MAKE_TL_LIBRARY
 
-!msvc {
-  LIBS += -lz
-}
-
-msvc {
-
-  LIBS += \
-    -L$$THIRD_PARTY/zlib/1.2.11/lib -lzlib
-
-}
-
-equals(HAVE_QT, "0") {
-  LIBS += -lpthread
-}
-
-equals(HAVE_CURL, "1") {
-  LIBS += -lcurl
-  win32 {
-    LIBS += -lwsock32    # required because we do "select"
-  }
-}
-
-equals(HAVE_EXPAT, "1") {
-  LIBS += -lexpat
-}
-
 FORMS =
 
 SOURCES = \