diff --git a/hw/bsp/brtmm90x/family.mk b/hw/bsp/brtmm90x/family.mk
index f45e27cb5..0ddf47a3a 100644
--- a/hw/bsp/brtmm90x/family.mk
+++ b/hw/bsp/brtmm90x/family.mk
@@ -8,7 +8,7 @@ ifeq ($(FT9XX_PREBUILT_LIBS),1)
 # If the FT90X toolchain is installed on Windows systems then the SDK 
 # include files and prebuilt libraries are at: %FT90X_TOOLCHAIN%/hardware
 FT9XX_SDK = $(FT90X_TOOLCHAIN)/hardware
-INC += $(FT9XX_SDK)/include
+INC += "$(FT9XX_SDK)/include"
 else
 # The submodule BRTSG-FOSS/ft90x-sdk contains header files and source
 # code for the Bridgetek SDK. This can be used instead of the prebuilt
@@ -16,7 +16,7 @@ else
 DEPS_SUBMODULES += hw/mcu/bridgetek/ft9xx/ft90x-sdk
 # The SDK can be used to load specific files from the Bridgetek SDK.
 FT9XX_SDK = hw/mcu/bridgetek/ft9xx/ft90x-sdk/Source
-INC += $(TOP)/$(FT9XX_SDK)/include
+INC += "$(TOP)/$(FT9XX_SDK)/include"
 endif
 
 # Add include files which are within the TinyUSB directory structure.