diff --git a/poly2tri/common/shapes.cc b/poly2tri/common/shapes.cc
index d0de13e..f3471dd 100644
--- a/poly2tri/common/shapes.cc
+++ b/poly2tri/common/shapes.cc
@@ -29,6 +29,8 @@
  * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 #include "shapes.h"
+
+#include <cassert>
 #include <iostream>
 
 namespace p2t {
@@ -362,4 +364,4 @@ void Triangle::DebugPrint()
   cout << points_[2]->x << "," << points_[2]->y << endl;
 }
 
-}
\ No newline at end of file
+}
diff --git a/poly2tri/common/shapes.h b/poly2tri/common/shapes.h
index aa582b1..e72cefa 100644
--- a/poly2tri/common/shapes.h
+++ b/poly2tri/common/shapes.h
@@ -33,10 +33,10 @@
 #ifndef SHAPES_H
 #define SHAPES_H
 
-#include <vector>
-#include <cstddef>
-#include <assert.h>
 #include <cmath>
+#include <cstddef>
+#include <stdexcept>
+#include <vector>
 
 namespace p2t {
 
@@ -136,7 +136,7 @@ struct Edge {
         p = &p2;
       } else if (p1.x == p2.x) {
         // Repeat points
-        assert(false);
+        throw std::runtime_error("Edge::Edge: p1 == p2");
       }
     }
 
@@ -320,4 +320,4 @@ inline void Triangle::IsInterior(bool b)
 
 }
 
-#endif
\ No newline at end of file
+#endif
diff --git a/poly2tri/sweep/advancing_front.cc b/poly2tri/sweep/advancing_front.cc
index 38723be..37e832d 100644
--- a/poly2tri/sweep/advancing_front.cc
+++ b/poly2tri/sweep/advancing_front.cc
@@ -30,6 +30,8 @@
  */
 #include "advancing_front.h"
 
+#include <cassert>
+
 namespace p2t {
 
 AdvancingFront::AdvancingFront(Node& head, Node& tail)
@@ -105,4 +107,4 @@ AdvancingFront::~AdvancingFront()
 {
 }
 
-}
\ No newline at end of file
+}
diff --git a/poly2tri/sweep/sweep.cc b/poly2tri/sweep/sweep.cc
index e31ffde..2f4cf24 100644
--- a/poly2tri/sweep/sweep.cc
+++ b/poly2tri/sweep/sweep.cc
@@ -28,12 +28,14 @@
  * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
  * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
-#include <stdexcept>
 #include "sweep.h"
 #include "sweep_context.h"
 #include "advancing_front.h"
 #include "../common/utils.h"
 
+#include <cassert>
+#include <stdexcept>
+
 namespace p2t {
 
 // Triangulate simple polygon with holes