diff --git a/tostadas/4.0.0/Dockerfile b/tostadas/4.0.0/Dockerfile
index fc1d0eb56..c7a56b1c7 100644
--- a/tostadas/4.0.0/Dockerfile
+++ b/tostadas/4.0.0/Dockerfile
@@ -34,7 +34,7 @@ RUN wget https://github.com/CDCgov/tostadas/archive/refs/tags/v${TOSTADAS_VER}.t
 
 # use mamba to install conda packages
 RUN micromamba env create -f tostadas/environment.yml && \
-    micromamba clean -a -y && \
+    micromamba clean -a -y -f && \
     echo "source activate tostadas" > ~/.bashrc && \
     rm -rf /tostadas
 
@@ -55,4 +55,4 @@ FROM app as test
 RUN liftoff --version && \
     samtools --version && \
     python --version && \
-    table2asn -help
\ No newline at end of file
+    table2asn -help