diff --git a/io_export_paper_model.py b/io_export_paper_model.py
index 39d6b508d3ff24b1fae2865ea2fc0eca224a0af2..39b65505e6de6ce5ea1a052bda1c8e96fbb2ebc0 100644
--- a/io_export_paper_model.py
+++ b/io_export_paper_model.py
@@ -12,7 +12,7 @@
 bl_info = {
     "name": "Export Paper Model",
     "author": "Addam Dominec",
-    "version": (1, 0),
+    "version": (1, 1),
     "blender": (2, 80, 0),
     "location": "File > Export > Paper Model",
     "warning": "",
@@ -703,7 +703,9 @@ class Edge:
         if not normal_a or not normal_b:
             self.angle = -3  # just a very sharp angle
         else:
-            self.angle = asin(normal_a.cross(normal_b).dot(self.vector.normalized()))
+            s = normal_a.cross(normal_b).dot(self.vector.normalized())
+            s = max(min(s, 1.0), -1.0) # deal with rounding errors
+            self.angle = asin(s)
             if loop_a.link_loop_next.vert != loop_b.vert or loop_b.link_loop_next.vert != loop_a.vert:
                 self.angle = abs(self.angle)