diff --git a/Dockerfile b/Dockerfile
index 147c362d..2649efac 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -3,6 +3,7 @@ FROM ubuntu:20.04
 
 # Avoid prompts from apt-get
 ARG DEBIAN_FRONTEND=noninteractive
+ARG NTHREADS=18
 
 RUN apt-get update && apt-get install -y software-properties-common
 RUN add-apt-repository ppa:ubuntu-toolchain-r/test -y && apt-get update
@@ -34,7 +35,7 @@ RUN cd blocksci && \
     mkdir build && \
     cd build && \
     CC=gcc-7 CXX=g++-7 cmake -DCMAKE_BUILD_TYPE=Release .. && \
-    make -j258 && \
+    make -j${NTHREADS} && \
     make install
 
 
diff --git a/README.md b/README.md
index c9094474..ba6c8a9e 100644
--- a/README.md
+++ b/README.md
@@ -15,8 +15,9 @@ To run BlockSci in Docker, the following steps are required:
 1. Clone this repository
     1. You also need to clone with submodules. For that, either use `--recurse-submodules` while cloning, or, in the cloned repository, follow with `git submodule init` and `git submodule update --recursive`.
 2. Install [Docker](https://docs.docker.com/get-docker/)
-3. Build the Docker image by running `docker build -t blocksci-cj .` in the root of the repository. This is just an initial setup to get all the libraries, and the *real* compilation will happen later.
+3. Build the Docker image by running `docker build --build-arg NTHREADS=<number of threads> -t blocksci-cj .` in the root of the repository. This is just an initial setup to get all the libraries, and the *real* compilation will happen later.
     1. We use `uv` to speed up the `blockscipy` installation, since it takes a long time.
+    2. Use NTHREADS build argument to control how many threads are used (passed to `make -j${NTHREADS}`).
 
 Now - since BlockSci is a memory-intensive and disk-consuming tool, we **strongly** recommend you to not hold the BlockSci data directly in the image, but to mount a persistent volume to the container.