diff --git a/lib/spack/docs/containers.rst b/lib/spack/docs/containers.rst
index 2ca25b7207b..fe678fd76d4 100644
--- a/lib/spack/docs/containers.rst
+++ b/lib/spack/docs/containers.rst
@@ -165,7 +165,7 @@ of environments:
        # Extra instructions
        extra_instructions:
          final: |
-   RUN echo 'export PS1="\[$(tput bold)\]\[$(tput setaf 1)\][gromacs]\[$(tput setaf 2)\]\u\[$(tput sgr0)\]:\w $ \[$(tput sgr0)\]"' >> ~/.bashrc
+           RUN echo 'export PS1="\[$(tput bold)\]\[$(tput setaf 1)\][gromacs]\[$(tput setaf 2)\]\u\[$(tput sgr0)\]:\w $ \[$(tput sgr0)\]"' >> ~/.bashrc
 
        # Labels for the image
        labels: