diff --git a/.circleci/config.yml b/.circleci/config.yml
index f14f580..7da06f6 100644
--- a/.circleci/config.yml
+++ b/.circleci/config.yml
@@ -11,7 +11,7 @@ jobs:
     steps:
       - run: apt-get update && apt-get install -y software-properties-common git ssh wget
       - run: add-apt-repository ppa:deadsnakes/ppa
-      - run: apt-get update && apt-get install -y python3.7 python3.7-dev build-essential
+      - run: apt-get update && apt-get install -y python3.7 python3.7-dev build-essential pkg-config libffi-dev
       - run: wget https://bootstrap.pypa.io/get-pip.py -O /tmp/get-pip.py
       - run: python3.7 /tmp/get-pip.py
       - run: python3.7 -m pip install pip==18.0  # downgrade pip to work around https://github.com/pypa/pipenv/issues/2924
@@ -41,7 +41,7 @@ jobs:
       - run: apt-get update && apt-get install -y software-properties-common git ssh
       - run: add-apt-repository ppa:team-gcc-arm-embedded/ppa
       - run: add-apt-repository ppa:deadsnakes/ppa
-      - run: apt-get update && apt-get install -y gcc-arm-embedded gettext wget unzip rsync python3.7 python3.7-dev build-essential
+      - run: apt-get update && apt-get install -y gcc-arm-embedded gettext wget unzip rsync python3.7 python3.7-dev build-essential pkg-config libffi-dev
       - run: wget https://bootstrap.pypa.io/get-pip.py -O /tmp/get-pip.py
       - run: python3.7 /tmp/get-pip.py
       - run: python3.7 -m pip install pip==18.0  # downgrade pip to work around https://github.com/pypa/pipenv/issues/2924
@@ -66,7 +66,7 @@ jobs:
       - run: apt-get update && apt-get install -y software-properties-common git ssh
       - run: add-apt-repository ppa:team-gcc-arm-embedded/ppa
       - run: add-apt-repository ppa:deadsnakes/ppa
-      - run: apt-get update && apt-get install -y gcc-arm-embedded gettext wget unzip rsync python3.7 python3.7-dev build-essential
+      - run: apt-get update && apt-get install -y gcc-arm-embedded gettext wget unzip rsync python3.7 python3.7-dev build-essential pkg-config libffi-dev
       - run: wget https://bootstrap.pypa.io/get-pip.py -O /tmp/get-pip.py
       - run: python3.7 /tmp/get-pip.py
       - run: python3.7 -m pip install pip==18.0  # downgrade pip to work around https://github.com/pypa/pipenv/issues/2924
@@ -92,7 +92,7 @@ jobs:
       - run: apt-get update && apt-get install -y software-properties-common git ssh
       - run: add-apt-repository ppa:team-gcc-arm-embedded/ppa
       - run: add-apt-repository ppa:deadsnakes/ppa
-      - run: apt-get update && apt-get install -y gcc-arm-embedded gettext wget unzip rsync python3.7 python3.7-dev build-essential
+      - run: apt-get update && apt-get install -y gcc-arm-embedded gettext wget unzip rsync python3.7 python3.7-dev build-essential pkg-config libffi-dev
       - run: wget https://bootstrap.pypa.io/get-pip.py -O /tmp/get-pip.py
       - run: python3.7 /tmp/get-pip.py
       - run: python3.7 -m pip install pip==18.0  # downgrade pip to work around https://github.com/pypa/pipenv/issues/2924
@@ -118,7 +118,7 @@ jobs:
       - run: apt-get update && apt-get install -y software-properties-common git ssh
       - run: add-apt-repository ppa:team-gcc-arm-embedded/ppa
       - run: add-apt-repository ppa:deadsnakes/ppa
-      - run: apt-get update && apt-get install -y gcc-arm-embedded gettext wget unzip rsync python3.7 python3.7-dev build-essential
+      - run: apt-get update && apt-get install -y gcc-arm-embedded gettext wget unzip rsync python3.7 python3.7-dev build-essential pkg-config libffi-dev
       - run: wget https://bootstrap.pypa.io/get-pip.py -O /tmp/get-pip.py
       - run: python3.7 /tmp/get-pip.py
       - run: python3.7 -m pip install pip==18.0  # downgrade pip to work around https://github.com/pypa/pipenv/issues/2924
diff --git a/Makefile b/Makefile
index 98d2c3c..f47f8e8 100644
--- a/Makefile
+++ b/Makefile
@@ -52,14 +52,14 @@ test: micropython-build-unix
 
 .circuitpy-deps: .submodules
 	@echo "===> Building circuitpython/mpy-cross"
-	@make -C build/circuitpython/mpy-cross
+	@pipenv run $(MAKE) -C build/circuitpython/mpy-cross
 	@echo "===> Pulling Nordic BLE stack"
 	@cd build/circuitpython/ports/nrf && ./drivers/bluetooth/download_ble_stack.sh 2>/dev/null >/dev/null
 	@touch .circuitpy-deps
 
 .micropython-deps: .submodules
 	@echo "===> Building micropython/mpy-cross"
-	@make -C build/micropython/mpy-cross
+	@pipenv run $(MAKE) -C build/micropython/mpy-cross
 	@touch .micropython-deps
 
 submodules: .submodules
@@ -147,7 +147,7 @@ circuitpy-flash-itsybitsy-m4-express:
 
 circuitpy-flash-nrf: circuitpy-build-nrf
 	@echo "===> Flashing CircuitPython with KMK and your keymap"
-	@make -C build/circuitpython/ports/nrf BOARD=feather_nrf52832 SERIAL=${AMPY_PORT} SD=s132 FROZEN_MPY_DIR=freeze dfu-gen dfu-flash
+	@pipenv run $(MAKE) -C build/circuitpython/ports/nrf BOARD=feather_nrf52832 SERIAL=${AMPY_PORT} SD=s132 FROZEN_MPY_DIR=freeze dfu-gen dfu-flash
 
 micropython-build-pyboard:
 	@pipenv run $(MAKE) -j4 -C build/micropython/ports/stm32/ BOARD=PYBV11 FROZEN_MPY_DIR=freeze all