diff --git a/src/Atlas.cpp b/src/Atlas.cpp
index cc07be2..546c74b 100644
--- a/src/Atlas.cpp
+++ b/src/Atlas.cpp
@@ -148,6 +148,9 @@ bool Atlas::generate(bool useCache,
                 msdf_atlas::FontGeometry _fontGeometry(&variationGlyphs);
                 fontGeometry = _fontGeometry;
 
+                // this function silently fails, if variation is not available
+                // which is absolutely fine, and allows to set a random
+                // variation step for non-variable fonts.
                 msdfgen::setFontVariationAxis(ft,
                                               font,
                                               variation.name.c_str(),