diff --git a/README.md b/README.md
index 5d3ff273..8542aa90 100644
--- a/README.md
+++ b/README.md
@@ -22,7 +22,7 @@ cmake --build build --config Release
 ```
 
 Note, if you are using custom installs of HDF5 or BOOST that are not being detected 
-automatically by cmake, you can specify `HDF5_ROOT` and `BOOST_ROOT` variables to 
+automatically by cmake, you can specify `HDF5_ROOT` and `BOOST_ROOT` environment variables to 
 point to install directories of HDF5 and BOOST respectively.