diff --git a/sklearn/decomposition/tests/test_pca.py b/sklearn/decomposition/tests/test_pca.py
index d2c5452c10461..65624215b1158 100644
--- a/sklearn/decomposition/tests/test_pca.py
+++ b/sklearn/decomposition/tests/test_pca.py
@@ -532,6 +532,9 @@ def check_pca_float_dtype_preservation(svd_solver):
     assert pca_64.transform(X_64).dtype == np.float64
     assert pca_32.transform(X_32).dtype == np.float32
 
+    # the rtol is set such that the test passes on all platforms tested on
+    # conda-forge: PR#15775
+    # see: https://github.com/conda-forge/scikit-learn-feedstock/pull/113
     assert_allclose(pca_64.components_, pca_32.components_, rtol=2e-4)