diff --git a/Dockerfile b/Dockerfile
index b28ab41..aac7a51 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -1,5 +1,5 @@
 FROM debian:trixie-slim AS build
-RUN apt-get update && apt-get install -y make gcc gcc chicken-bin git
+RUN apt-get update && apt-get install -y make gcc chicken-bin git
 RUN chicken-install r7rs
 
 WORKDIR /build
@@ -21,4 +21,4 @@ RUN make PREFIX=/opt/compile-r7rs install
 
 FROM debian:trixie-slim
 COPY --from=build /opt/compile-r7rs /opt/compile-r7rs
-ENV PATH=/opt/compile-r7rs:${PATH}
+ENV PATH=/opt/compile-r7rs/bin:${PATH}
diff --git a/Dockerfile.alpine b/Dockerfile.alpine
index 02f87b4..5a62c22 100644
--- a/Dockerfile.alpine
+++ b/Dockerfile.alpine
@@ -21,4 +21,4 @@ RUN make PREFIX=/opt/compile-r7rs install
 
 FROM alpine
 COPY --from=build /opt/compile-r7rs /opt/compile-r7rs
-ENV PATH=/opt/compile-r7rs:${PATH}
+ENV PATH=/opt/compile-r7rs/bin:${PATH}
diff --git a/compile-r7rs.scm b/compile-r7rs.scm
index 15f0b1f..fa2cd10 100644
--- a/compile-r7rs.scm
+++ b/compile-r7rs.scm
@@ -27,7 +27,10 @@
 (define scheme (if (get-environment-variable "COMPILE_R7RS")
                   (string->symbol (get-environment-variable "COMPILE_R7RS"))
                   #f))
-(when (not scheme) (error "Environment variable COMPILE_R7RS not set."))
+(when (not scheme)
+  (display "Environment variable COMPILE_R7RS not set." (current-error-port))
+  (newline (current-error-port))
+  (exit 1))
 (when (not (assoc scheme data)) (error "Unsupported implementation" scheme))
 (define compilation-target (if (get-environment-variable "TARGET")
                              (get-environment-variable "TARGET")