diff --git a/src/hb-ot-shape-complex-khmer-machine.rl b/src/hb-ot-shape-complex-khmer-machine.rl
index c63859330..094a82928 100644
--- a/src/hb-ot-shape-complex-khmer-machine.rl
+++ b/src/hb-ot-shape-complex-khmer-machine.rl
@@ -53,7 +53,6 @@ DOTTEDCIRCLE = 12;
 RS    = 13;
 Coeng = 14;
 Ra    = 16;
-CM    = 17;
 Symbol= 18;
 
 c = (C | Ra);			# is_consonant
@@ -67,15 +66,14 @@ syllable_tail = (z?.SM.SM?.ZWNJ?)? A{0,3}? VD{0,2};
 place_holder = PLACEHOLDER | DOTTEDCIRCLE;
 halant_group = (z?.Coeng.(ZWJ.N?)?);
 final_halant_group = halant_group | Coeng.ZWNJ;
-medial_group = CM?;
 halant_or_matra_group = (final_halant_group | (Coeng.ZWJ)? matra_group{0,4}) (Coeng (cn|V))?;
 
 
-consonant_syllable =	(cn.halant_group){0,4} cn medial_group halant_or_matra_group syllable_tail;
-vowel_syllable =	V.n? (ZWJ | (halant_group.cn){0,4} medial_group halant_or_matra_group syllable_tail);
-standalone_cluster =	(PLACEHOLDER | DOTTEDCIRCLE).n? (halant_group.cn){0,4} medial_group halant_or_matra_group syllable_tail;
+consonant_syllable =	(cn.halant_group){0,4} cn halant_or_matra_group syllable_tail;
+vowel_syllable =	V.n? (ZWJ | (halant_group.cn){0,4} halant_or_matra_group syllable_tail);
+standalone_cluster =	(PLACEHOLDER | DOTTEDCIRCLE).n? (halant_group.cn){0,4} halant_or_matra_group syllable_tail;
 symbol_cluster = 	symbol syllable_tail;
-broken_cluster =	n? (halant_group.cn){0,4} medial_group halant_or_matra_group syllable_tail;
+broken_cluster =	n? (halant_group.cn){0,4} halant_or_matra_group syllable_tail;
 other =			any;
 
 main := |*