diff --git a/README.md b/README.md
index a601420b4faac62715b9805843e048d71a47b5ec..f3299e2986cdfb17a68e429d593da108f5a2ed37 100644
--- a/README.md
+++ b/README.md
@@ -16,7 +16,7 @@ more details about Renku.
 
 So, the stack to build the images that work on Renku is a bit convoluted, so here is a description of the layers of layers that are involved. This is mostly left as a memento to remind myself how I did it. If I were to do it again, it would probably be worth organizing it all into one github repo.
 
-First, we took an image from rocker (I think Carl Boettiger is to thank for these) and I uploaded it to my own dockerhub, like this:
+First, we took an image from rocker (I think Carl Boettiger is to thank for these; these were freshly built following the recent change to `R 4.0.0`) and I uploaded it to my own dockerhub, like this:
 
 ```
 docker pull rockerdev/rstudio:4.0.0
@@ -32,6 +32,8 @@ docker tag bioconductor_docker:4.0.0 markrobinsonuzh/renku:r4.0.0_bioc
 docker push markrobinsonuzh/renku:r4.0.0_bioc
 ```
 
+Note: [markrobinsonuzh/bioconductor_docker](https://github.com/markrobinsonuzh/bioconductor_docker) is forked from [Bioconductor/bioconductor_docker](https://github.com/Bioconductor/bioconductor_docker).
+
 Next, using Renku's previous docker builds (I'll thank Rok and Emma and Christine here, possibly others!), the tools that are needed under the hood of Renku are added:
 
 ```
@@ -39,7 +41,9 @@ docker build -t markrobinsonuzh/renku:r4.0.0_bioc_renku https://github.com/markr
 docker push markrobinsonuzh/renku:r4.0.0_bioc_renku
 ```
 
-And then, it's _just_ Renku:
+Note: [markrobinsonuzh/renkulab-docker](https://github.com/markrobinsonuzh/renkulab-docker) is forked from [SwissDataScienceCenter/renkulab-docker](https://github.com/SwissDataScienceCenter/renkulab-docker).
+
+And then, it's _just_ from Renku:
 
 ```
 docker build -t markrobinsonuzh/renku:r4.0.0_bioc_renku_bio334ss2020 https://renkulab.io/gitlab/mark.robinson/bio334_spring2020.git