diff --git a/otl/gsub-ligation.ptl b/otl/gsub-ligation.ptl
index da5104905..f05f6b2cf 100644
--- a/otl/gsub-ligation.ptl
+++ b/otl/gsub-ligation.ptl
@@ -525,18 +525,14 @@ define [buildLigationsImpl sink para glyphs featureName mappedFeature rankedLook
 				local stickTermLeft  {}
 				local stickConnLeft  {}
 				foreach [lc : items-of {'l' 'l1' 'j' 'j1' 'c' 'z'}] : begin
-					local freeCls : [CBar "\(lc)f"] barCls
-					foreach [g : items-of freeCls] : if glyphs.(g) : stickTermLeft.push g
-					local connCls : [CBar "\(lc)c"] barCls
-					foreach [g : items-of connCls] : if glyphs.(g) : stickConnLeft.push g
+					set stickTermLeft : stickTermLeft.concat : [CBar "\(lc)f"] barCls
+					set stickConnLeft : stickConnLeft.concat : [CBar "\(lc)c"] barCls
 
 				local stickTermRight {}
 				local stickConnRight {}
 				foreach [rc : items-of {'r' 'r1' 'j' 'j1' 'c' 'z'}] : begin
-					local freeCls : [CBar "f\(rc)"] barCls
-					foreach [g : items-of freeCls] : if glyphs.(g) : stickTermRight.push g
-					local connCls : [CBar "c\(rc)"] barCls
-					foreach [g : items-of connCls] : if glyphs.(g) : stickConnRight.push g
+					set stickTermRight : stickTermRight.concat : [CBar "f\(rc)"] barCls
+					set stickConnRight : stickConnRight.concat : [CBar "c\(rc)"] barCls
 
 				CreateLigationLookup : list
 					chain-rule
diff --git a/otl/table-util.ptl b/otl/table-util.ptl
index 4d315c731..c0898a531 100644
--- a/otl/table-util.ptl
+++ b/otl/table-util.ptl
@@ -1,6 +1,7 @@
 export : define [CreateEmptyTable] {.languages {.} .features {.} .lookups {.}}
 
 extern Map
+extern Set
 
 export : define [pick-language sink tag] : begin
 	if sink.languages.(tag) : return sink.languages.(tag)
@@ -112,7 +113,7 @@ export : define [ChainRuleBuilder sink] : begin
 			set founde true
 		foreach [j : range 0 terms.length] : begin
 			local term terms.(j)
-			subtable.match.push term.left
+			subtable.match.push : Array.from : new Set term.left
 			local lutn : getSubLookup term.left term.right
 			if lutn : subtable.apply.push {.at j .lookup lutn}
 		return subtable