diff --git a/Dockerfile.test b/Dockerfile.test
index b79be3a..ee6029a 100644
--- a/Dockerfile.test
+++ b/Dockerfile.test
@@ -1,22 +1,24 @@
 ARG SCHEME=chibi
 ARG IMAGE=chibi:head
-FROM docker.io/debian:trixie-slim AS local-chibi
-RUN apt-get update && apt-get install -y git ca-certificates make gcc libc-dev
-#RUN git clone https://github.com/ashinn/chibi-scheme.git --depth=1
-RUN git clone https://github.com/Retropikzel/chibi-scheme.git --branch gauche-fixes --depth=1
-RUN cd chibi-scheme && make DESTDIR=/opt/chibi -j16 && make DESTDIR=/opt/chibi -j16 install
+FROM schemers/${IMAGE}
+FROM debian:trixie AS build
+WORKDIR /debs
+RUN apt-get update && apt-get install \
+    -y \
+    --no-install-recommends \
+    --no-install-suggests \
+    --download-only \
+    gcc libffi-dev libc-dev cmark make linux-libc-dev
 
 ARG SCHEME=chibi
 ARG IMAGE=chibi:head
-FROM docker.io/schemers/${IMAGE}
-RUN apt-get update && apt-get install -y make gcc markdown libffi-dev
-COPY --from=local-chibi /opt/chibi /opt/chibi
-COPY --from=docker.io/retropikzel1/compile-r7rs /opt/compile-r7rs /opt/compile-r7rs
+FROM schemers/${IMAGE}
+COPY --from=build /var/cache/apt/archives/*.deb /debs/
+RUN dpkg -i /debs/*.deb
+COPY --from=retropikzel1/compile-r7rs /opt/compile-r7rs /opt/compile-r7rs
+ENV PATH=${PATH}:/opt/compile-r7rs/bin:/build/usr/bin
 ARG SCHEME=chibi
 ENV COMPILE_R7RS=${SCHEME}
 ENV GUILE_AUTO_COMPILE=0
 RUN mkdir -p ${HOME}/.snow && echo "()" > ${HOME}/.snow/config.scm
-ENV CHIBI_MODULE_PATH=/opt/chibi/usr/local/share/chibi:/opt/chibi/usr/local/lib/chibi
-ENV LD_LIBRARY_PATH=/opt/chibi/usr/local/lib:/opt/chibi/usr/local/lib/chibi
-ENV PATH=/opt/compile-r7rs/bin:/opt/chibi/usr/local/bin:${PATH}
 
diff --git a/Jenkinsfile b/Jenkinsfile
index 219b153..12d4ee6 100644
--- a/Jenkinsfile
+++ b/Jenkinsfile
@@ -2,7 +2,7 @@ def tests = ['primitives', 'array', 'struct', 'addressof', 'callback']
 
 pipeline {
     agent {
-        label 'linux'
+        label 'docker-x86_64'
     }
 
     options {
@@ -11,6 +11,11 @@ pipeline {
     }
 
     stages {
+
+        stage('Cache warmup') {
+            sh "docker build --build-arg IMAGE=chibi:head --build-arg SCHEME=chibi --tag=foreign-c-test-chibi -f Dockerfile.test ."
+        }
+
         stage('Tests') {
             steps {
                 script {
diff --git a/Makefile b/Makefile
index 99f003c..edabbe0 100644
--- a/Makefile
+++ b/Makefile
@@ -1,12 +1,13 @@
 .PHONY: libtest.o tests/libtest.so libtest.a documentation README.html foreign-c.pdf
 PDFENGINE=weasyprint
-CC=gcc
 VERSION=0.10.6
 TEST=primitives
 SCHEME=chibi
 TMPDIR=tmp/${SCHEME}
 SNOW_CHIBI_ARGS=""
 DOCKERIMG=${SCHEME}:head
+CC=gcc
+
 ifeq "${SCHEME}" "chicken"
 DOCKERIMG="chicken:5"
 endif
@@ -42,32 +43,34 @@ test: ${TMPDIR}/test/libtest.o ${TMPDIR}/test/libtest.so ${TMPDIR}/test/libtest.
 		COMPILE_R7RS_CHICKEN="-L -ltest -I. -L." \
 		COMPILE_R7RS=${SCHEME} \
 		compile-r7rs -o ${TEST} ${TEST}.scm
-	cd ${TMPDIR}/test \ && timeout 60 printf "\n" | LD_LIBRARY_PATH=. ./${TEST}
+	cd ${TMPDIR}/test \ && printf "\n" | LD_LIBRARY_PATH=. ./${TEST}
 
 test-docker:
 	docker build --build-arg IMAGE=${DOCKERIMG} --build-arg SCHEME=${SCHEME} --tag=foreign-c-test-${SCHEME} -f Dockerfile.test .
-	docker run -it -v "${PWD}:/workdir" -w /workdir -t foreign-c-test-${SCHEME} sh -c "make SCHEME=${SCHEME} TEST=${TEST} SNOW_CHIBI_ARGS=--always-yes install test"
+	docker run -it -v "${PWD}:/workdir" -w /workdir -t foreign-c-test-${SCHEME} sh -c \
+		"timeout 120 make SCHEME=${SCHEME} TEST=${TEST} SNOW_CHIBI_ARGS=--always-yes install test"
 
 ${TMPDIR}/test/libtest.o: tests/c-src/libtest.c
 	mkdir -p ${TMPDIR}/test
-	${CC} -o ${TMPDIR}/test/libtest.o -fPIC -c tests/c-src/libtest.c -I./include
+	${CC} ${CFLAGS} -o ${TMPDIR}/test/libtest.o -fPIC -c tests/c-src/libtest.c -I./include ${LDFLAGS}
 
 ${TMPDIR}/test/libtest.so: tests/c-src/libtest.c
 	mkdir -p ${TMPDIR}/test
-	${CC} -o ${TMPDIR}/test/libtest.so -shared -fPIC tests/c-src/libtest.c -I./include
+	${CC} ${CFLAGS} -o ${TMPDIR}/test/libtest.so -shared -fPIC tests/c-src/libtest.c -I./include ${LDFLAGS}
 
 ${TMPDIR}/test/libtest.a: ${TMPDIR}/test/libtest.o tests/c-src/libtest.c
-	ar rcs ${TMPDIR}/test/libtest.a ${TMPDIR}/test/libtest.o
+	ar rcs ${TMPDIR}/test/libtest.a ${TMPDIR}/test/libtest.o ${LDFLAGS}
 
 ${TMPDIR}:
 	mkdir -p ${TMPDIR}
 
 README.html: README.md
-	markdown README.md > README.html
+	cmark README.md > README.html
 
 chibi: foreign/c/primitives/chibi/foreign-c.stub
 	chibi-ffi foreign/c/primitives/chibi/foreign-c.stub
 	${CC} \
+		${CFLAGS} \
 		-g3 \
 		-o foreign/c/primitives/chibi/foreign-c.so \
 		foreign/c/primitives/chibi/foreign-c.c \
@@ -79,7 +82,7 @@ gauche:
 	gauche-package compile \
 		--srcdir=foreign/c/primitives/gauche \
 		--cc=${CC} \
-		--cflags="-I.foreign/c/primitives/gauche" \
+		--cflags="${CFLAGS} -I.foreign/c/primitives/gauche" \
 		--libs=-lffi \
 		foreign-c-primitives-gauche foreign-c-primitives-gauche.c gauchelib.scm
 	mkdir -p foreign/c/lib
diff --git a/README.md b/README.md
index b992103..2a86ad2 100644
--- a/README.md
+++ b/README.md
@@ -194,6 +194,7 @@ library directory.
 
 Example for how to install for Gauche:
 
+    apt-get install libffi-dev
     git clone https://git.sr.ht/~retropikzel/foreign-c
     cd foreign-c
     make SCHEME=gauche