diff --git a/dockerfiles/Dockerfile.snow-chibi-install-test b/dockerfiles/Dockerfile.snow-chibi-install-test
index 91394ec..2c88e11 100644
--- a/dockerfiles/Dockerfile.snow-chibi-install-test
+++ b/dockerfiles/Dockerfile.snow-chibi-install-test
@@ -17,4 +17,6 @@ RUN cd chibi-scheme && make && make install
 RUN chicken-install r7rs
 RUN git clone https://gitea.scheme.org/Retropikzel/compile-r7rs.git --depth=1
 RUN cd compile-r7rs && make && make install
+ARG COMPILE_R7RS=chibi
+ENV COMPILE_R7RS=${COMPILE_R7RS}
 
diff --git a/dockerfiles/Dockerfile.test b/dockerfiles/Dockerfile.test
index 9cf0d4e..59de740 100644
--- a/dockerfiles/Dockerfile.test
+++ b/dockerfiles/Dockerfile.test
@@ -15,4 +15,6 @@ RUN apt-get update && apt-get install -y \
 RUN chicken-install r7rs
 RUN git clone https://gitea.scheme.org/Retropikzel/compile-r7rs.git --depth=1
 RUN cd compile-r7rs && make && make install
+ARG COMPILE_R7RS=chibi
+ENV COMPILE_R7RS=${COMPILE_R7RS}