diff --git a/asyn/Makefile b/asyn/Makefile
index 60890015..fda46d42 100644
--- a/asyn/Makefile
+++ b/asyn/Makefile
@@ -263,11 +263,26 @@ ifeq ($(DRV_FTDI),YES)
   asyn_SYS_LIBS += usb-1.0
   INC += drvAsynFTDIPort.h
   ifeq ($(DRV_FTDI_USE_LIBFTDI1),YES)
-    asyn_SYS_LIBS += ftdi1
     USR_CXXFLAGS += -DHAVE_LIBFTDI1
+    ifeq ($(FTDI_LIB),)
+      asyn_SYS_LIBS += ftdi1
+    else
+      asyn_LIBS += ftdi1
+      ftdi1_DIR = $(FTDI_LIB)
+    endif
   else
-    asyn_SYS_LIBS += ftdi
+    ifeq ($(FTDI_LIB),)
+      asyn_SYS_LIBS += ftdi
+    else
+      asyn_LIBS += ftdi
+      ftdi_DIR = $(FTDI_LIB)
+    endif
   endif
+
+  ifdef FTDI_INCLUDE
+    USR_INCLUDES += $(addprefix -I, $(FTDI_INCLUDE))
+  endif
+
   DBD += drvAsynFTDIPort.dbd
 endif