diff --git a/build/amd64-ubuntu-builder.dockerfile b/build/amd64-ubuntu-builder.dockerfile
index 1f78647..317e5e2 100644
--- a/build/amd64-ubuntu-builder.dockerfile
+++ b/build/amd64-ubuntu-builder.dockerfile
@@ -13,8 +13,7 @@ RUN set -x \
        rsync \
        gdb \
        gdbserver \
-       valgrind \
-  && rm -rf /var/lib/apt/lists/*
+       valgrind
 
 COPY src /usr/local/src
 
diff --git a/build/arm32v7-ubuntu-builder.dockerfile b/build/arm32v7-ubuntu-builder.dockerfile
index 295b2f2..e0a1f31 100644
--- a/build/arm32v7-ubuntu-builder.dockerfile
+++ b/build/arm32v7-ubuntu-builder.dockerfile
@@ -14,8 +14,7 @@ RUN set -x \
        pkg-config \
        rsync \
        gdb \
-       gdbserver \
-  && rm -rf /var/lib/apt/lists/*
+       gdbserver
 
 COPY src /usr/local/src