diff --git a/arrays.scad b/arrays.scad
index af6bd65..1cb0947 100644
--- a/arrays.scad
+++ b/arrays.scad
@@ -276,6 +276,40 @@ function deduplicate(list, closed=false, eps=EPSILON) =
 		[for (i=[0:1:l-1]) if (i==end || list[i] != list[(i+1)%l]) list[i]];
 
 
+// Function: deduplicate_indexed()
+// Usage:
+//   new_idxs = deduplicate_indexed(list, indices, [closed], [eps]);
+// Description:
+//   Given a list, and indices into it, removes consecutive indices that
+//   index to the same values in the list.
+// Arguments:
+//   list = The list that the indices index into.
+//   indices = The list of indices to deduplicate.
+//   closed = If true, drops trailing indices if what they index matches what the first index indexes.
+//   eps = The maximum difference to allow between numbers or vectors.
+// Examples:
+//   deduplicate_indexed([8,6,4,6,3], [1,4,3,1,2,2,0,1]);  // Returns: [1,4,3,2,0,1]
+//   deduplicate_indexed([8,6,4,6,3], [1,4,3,1,2,2,0,1], closed=true);  // Returns: [1,4,3,2,0]
+function deduplicate_indexed(list, indices, closed=false, eps=EPSILON) =
+	assert(is_list(list)||is_string(list))
+	assert(indices==[] || is_vector(indices))
+	indices==[]? [] :
+	let(
+		l = len(indices),
+		end = l-(closed?0:1)
+	) [
+		for (i = [0:1:l-1]) let(
+			a = list[indices[i]],
+			b = list[indices[(i+1)%l]],
+			eq = (a == b)? true :
+				(a*0 != b*0)? false :
+				is_num(a)? approx(a, b, eps=eps) :
+				is_vector(a)? approx(a, b, eps=eps) :
+				false
+		) if (i==end || !eq) indices[i]
+	];
+
+
 // Function: repeat_entries()
 // Usage:
 //   newlist = repeat_entries(list, N)
diff --git a/tests/test_arrays.scad b/tests/test_arrays.scad
index 68009fc..b066049 100644
--- a/tests/test_arrays.scad
+++ b/tests/test_arrays.scad
@@ -90,6 +90,13 @@ module test_deduplicate() {
 test_deduplicate();
 
 
+module test_deduplicate_indexed() {
+	assert(deduplicate_indexed([8,6,4,6,3], [1,4,3,1,2,2,0,1]) == [1,4,1,2,0,1]);
+	assert(deduplicate_indexed([8,6,4,6,3], [1,4,3,1,2,2,0,1], closed=true) == [1,4,1,2,0]);
+}
+test_deduplicate_indexed();
+
+
 module test_list_set() {
 	assert(list_set([2,3,4,5], 2, 21) == [2,3,21,5]);
 	assert(list_set([2,3,4,5], [1,3], [81,47]) == [2,81,4,47]);
diff --git a/triangulation.scad b/triangulation.scad
index 3de4617..efa2eff 100644
--- a/triangulation.scad
+++ b/triangulation.scad
@@ -130,7 +130,7 @@ function is_only_noncolinear_vertex(points, facelist, vertex) =
 //   face = The face, given as a list of indices into the vertex array `points`.
 function triangulate_face(points, face) =
 	let(
-		face = deduplicate(face),
+		face = deduplicate_indexed(points,face),
 		count = len(face)
 	)
 	(count < 3)? [] :
diff --git a/version.scad b/version.scad
index b400bc6..5bb7003 100644
--- a/version.scad
+++ b/version.scad
@@ -8,7 +8,7 @@
 //////////////////////////////////////////////////////////////////////
 
 
-BOSL_VERSION = [2,0,221];
+BOSL_VERSION = [2,0,222];
 
 
 // Section: BOSL Library Version Functions