diff --git a/lib/Slic3r/ExtrusionPath.pm b/lib/Slic3r/ExtrusionPath.pm
index a006d8712..224cdf4be 100644
--- a/lib/Slic3r/ExtrusionPath.pm
+++ b/lib/Slic3r/ExtrusionPath.pm
@@ -187,10 +187,14 @@ sub detect_arcs {
             my $s2_angle = $s2->atan;
             my $s3_angle = $s3->atan;
             $s1_angle += 2*PI if $s1_angle < 0;
-            $s2_angle += 2*PI if $s2_angle < 0;
-            $s3_angle += 2*PI if $s3_angle < 0;
             my $s1s2_angle = $s2_angle - $s1_angle;
             my $s2s3_angle = $s3_angle - $s2_angle;
+            # allow -ve angles but constrain angles differences to 0<difference<2PI
+            $s1s2_angle -= 2*PI if ($s1s2_angle > 2*PI);
+            $s1s2_angle += 2*PI if ($s1s2_angle < -2*PI);
+            $s2s3_angle -= 2*PI if ($s2s3_angle > 2*PI);
+            $s2s3_angle += 2*PI if ($s2s3_angle < -2*PI);
+
             next if abs($s1s2_angle - $s2s3_angle) > $Slic3r::Geometry::parallel_degrees_limit;
             next if abs($s1s2_angle) < $Slic3r::Geometry::parallel_degrees_limit;     # ignore parallel lines
             next if $s1s2_angle > $max_angle;  # ignore too sharp vertices
@@ -203,10 +207,15 @@ sub detect_arcs {
                 my $line = Slic3r::Line->new($points[$j], $points[$j+1]);
                 last if abs($line->length - $s1_len) > $len_epsilon;
                 my $line_angle = $line->atan;
-                $line_angle += 2*PI if $line_angle < 0;
                 my $anglediff = $line_angle - $last_line_angle;
+                # allow -ve angles but constrain angle differences to 0<difference<2PI
+                $anglediff -= 2*PI if ($anglediff > 2*PI);
+                $anglediff += 2*PI if ($anglediff < -2*PI);
+
                 last if abs($s1s2_angle - $anglediff) > $Slic3r::Geometry::parallel_degrees_limit;
-                
+                # Do not try to be too ambitious. Just detect arcs up to 60 degrees.
+                # The algorithm for finding the center is not accurate enough for more than this
+                last if abs($s1_angle - $line_angle) > PI/6; 
                 # point $j+1 belongs to the arc
                 $arc_points[-1] = $points[$j+1];
                 $last_j = $j+1;