diff --git a/glyphs2fontir/src/glyphdata.rs b/glyphs2fontir/src/glyphdata.rs
index de3598c9..24687a6f 100644
--- a/glyphs2fontir/src/glyphdata.rs
+++ b/glyphs2fontir/src/glyphdata.rs
@@ -4,6 +4,7 @@
 
 use std::collections::HashSet;
 
+// Do a quick (relative to large match on str) check to see if this might be a mark
 #[inline(always)]
 pub(crate) fn might_be_a_nonspacing_mark_name(name: &str) -> bool {
     // shove the first 4 chars into a u32 and see if they could possibly be a nonspacing mark
@@ -698,6 +699,7 @@ pub(crate) fn is_nonspacing_mark_name(name: &str) -> bool {
     if name.len() > 35 || matches!(name.len(), 1 | 2) {
         return false;
     }
+    // fast exit: this can't possibly be a nonspacing mark
     if !might_be_a_nonspacing_mark_name(name) {
         return false;
     }
diff --git a/resources/scripts/non_spacing_marks.py b/resources/scripts/non_spacing_marks.py
index 10df9529..48aed5f3 100644
--- a/resources/scripts/non_spacing_marks.py
+++ b/resources/scripts/non_spacing_marks.py
@@ -82,6 +82,7 @@ def main(_):
         print(len(unique_prefix4s), "unique_prefix4s", sorted(unique_prefix4s))
 
         f.write("\n")
+        f.write("    // Do a quick (relative to large match on str) check to see if this might be a mark\n")
         f.write("#[inline(always)]\n")
         f.write(
             "pub(crate) fn might_be_a_nonspacing_mark_name(name: &str) -> bool {\n"
@@ -118,6 +119,7 @@ def main(_):
         # f.write("        return false;\n")
         # f.write("    };\n")
 
+        f.write("    // fast exit: this can't possibly be a nonspacing mark\n")
         f.write("    if !might_be_a_nonspacing_mark_name(name) {\n")
         f.write("        return false;\n")
         f.write("    }\n")