diff --git a/src/path/PathItem.Boolean.js b/src/path/PathItem.Boolean.js
index 3c00f450..18b0f76d 100644
--- a/src/path/PathItem.Boolean.js
+++ b/src/path/PathItem.Boolean.js
@@ -415,7 +415,26 @@ PathItem.inject(new function() {
         // Assign the average winding to the entire curve chain.
         var winding = Math.round(windingSum / 3);
         for (var j = chain.length - 1; j >= 0; j--) {
-            chain[j].segment._winding = winding;
+            var seg = chain[j].segment,
+                inter = seg._intersection,
+                wind = winding;
+            // We need to handle the edge cases of overlapping curves
+            // differently based on the type of operation, and adjust the
+            // winding number accordingly:
+            if (inter && inter._overlap) {
+                switch (operation) {
+                case 'unite':
+                    if (wind === 1)
+                        wind = 2;
+                    break;
+                case 'intersect':
+                    if (wind === 2)
+                        wind = 1;
+                    break;
+                }
+            }
+            seg._originalWinding = winding;
+            seg._winding = wind;
         }
     }
 
@@ -532,7 +551,7 @@ PathItem.inject(new function() {
                         && /^(unite|subtract)$/.test(operation)) {
                     // Switch to the overlapping intersecting segment if it is
                     // part of the boolean result.
-                    if (operator(other._winding)) {
+                    if (operator(other._originalWinding)) {
                         drawSegment(seg, 'overlap-cross', i, 'orange');
                         seg = other;
                     } else {