diff --git a/src/pixie/paths.nim b/src/pixie/paths.nim
index 9739a2f..4719508 100644
--- a/src/pixie/paths.nim
+++ b/src/pixie/paths.nim
@@ -683,9 +683,8 @@ proc commandsToShapes(
       ctrl2 * (-3*t3 + 3*t2) +
       to * (t3)
 
-    proc computeDerv(at, ctrl1, ctrl2, to: Vec2, t: float32): Vec2 {.inline.} =
-      let
-        t2 = t*t
+    proc computeDeriv(at, ctrl1, ctrl2, to: Vec2, t: float32): Vec2 {.inline.} =
+      let t2 = t*t
       at * (-3*t2 + 6*t - 3) +
       ctrl1 * (9*t2 - 12*t + 3) +
       ctrl2 * (-9*t2 + 6*t) +
@@ -703,11 +702,11 @@ proc commandsToShapes(
       let
         midpoint = (prev + next) / 2
         lineTangent = midpoint - prev
-        curveTangent = computeDerv(at, ctrl1, ctrl2, to, t + step / 2)
+        curveTangent = computeDeriv(at, ctrl1, ctrl2, to, t + step / 2)
         curveTangentScaled = curveTangent.normalize() * lineTangent.length()
-        error = (midpoint - halfway).lengthSq +
-          (lineTangent - curveTangentScaled).lengthSq
-      if error > errorMarginSq:
+        error = (midpoint - halfway).lengthSq
+        errorTangent = (lineTangent - curveTangentScaled).lengthSq
+      if error + errorTangent > errorMarginSq:
         next = halfway
         halfway = compute(at, ctrl1, ctrl2, to, t + step / 4)
         step /= 2
diff --git a/tests/paths/pathSwish.png b/tests/paths/pathSwish.png
new file mode 100644
index 0000000..a58993c
Binary files /dev/null and b/tests/paths/pathSwish.png differ
diff --git a/tests/test_path2.nim b/tests/test_path2.nim
deleted file mode 100644
index bc6f70a..0000000
--- a/tests/test_path2.nim
+++ /dev/null
@@ -1,12 +0,0 @@
-import chroma, pixie, pixie/fileformats/png, strformat
-
-block:
-  let
-    image = newImage(100, 100)
-    pathStr = """
-        M 40 40 L 40 80 L 80 80 L 80 40 C 80 -20 40 100 40 40
-    """
-    color = rgba(0, 0, 0, 255)
-  image.fill(rgba(255, 255, 255, 255))
-  image.fillPath(pathStr, color)
-  image.writeFile("tests/paths/pathSwish.png")
diff --git a/tests/test_paths.nim b/tests/test_paths.nim
index edd4faa..b5de9cc 100644
--- a/tests/test_paths.nim
+++ b/tests/test_paths.nim
@@ -773,3 +773,14 @@ block:
       mat3(),
       NonZero
     )
+
+block:
+  let
+    image = newImage(100, 100)
+    pathStr = """
+      M 40 40 L 40 80 L 80 80 L 80 40 C 80 -20 40 100 40 40
+    """
+    color = rgba(0, 0, 0, 255)
+  image.fill(rgba(255, 255, 255, 255))
+  image.fillPath(pathStr, color)
+  image.writeFile("tests/paths/pathSwish.png")