diff --git a/targets/nrf51.json b/targets/nrf51.json
index 60c0d5dc..9959c6f7 100644
--- a/targets/nrf51.json
+++ b/targets/nrf51.json
@@ -6,7 +6,8 @@
 		"--target=armv6m-none-eabi",
 		"-Qunused-arguments",
 		"-DNRF51",
-		"-I{root}/lib/CMSIS/CMSIS/Include"
+		"-I{root}/lib/CMSIS/CMSIS/Include",
+		"-I{root}/lib/nrfx/mdk"
 	],
 	"linkerscript": "targets/nrf51.ld",
 	"extra-files": [
diff --git a/targets/nrf52840.json b/targets/nrf52840.json
index 7afb2474..2c2eff7c 100644
--- a/targets/nrf52840.json
+++ b/targets/nrf52840.json
@@ -7,7 +7,8 @@
 		"-mfloat-abi=soft",
 		"-Qunused-arguments",
 		"-DNRF52840_XXAA",
-		"-I{root}/lib/CMSIS/CMSIS/Include"
+		"-I{root}/lib/CMSIS/CMSIS/Include",
+		"-I{root}/lib/nrfx/mdk"
 	],
 	"linkerscript": "targets/nrf52840.ld",
 	"extra-files": [