diff --git a/R/calculate_study_day.R b/R/derive_study_day.R
similarity index 100%
rename from R/calculate_study_day.R
rename to R/derive_study_day.R
diff --git a/tests/testthat/test-calculate_study_day.R b/tests/testthat/test-derive_study_day.R
similarity index 100%
rename from tests/testthat/test-calculate_study_day.R
rename to tests/testthat/test-derive_study_day.R