diff --git a/drawing.cpp b/drawing.cpp
index 7588f4d7..7ebf0fd2 100644
--- a/drawing.cpp
+++ b/drawing.cpp
@@ -786,7 +786,10 @@ ld get_width(dqi_poly* p) {
     return linewidthat(tC0(p->V)) * p->linewidth;
   }
 
+void debug_this() { }
+
 void dqi_poly::draw() {
+  if(flags & POLY_DEBUG) debug_this();
 
   dynamicval<ld> bs(hr::band_shift, band_shift);
   if(!hyperbolic && among(pmodel, mdPolygonal, mdPolynomial)) {
diff --git a/hyper.h b/hyper.h
index 9c40b52d..cb85c79f 100644
--- a/hyper.h
+++ b/hyper.h
@@ -5497,6 +5497,7 @@ static const int POLY_FORCE_INVERTED = (1<<20); // force inverted
 static const int POLY_ALWAYS_IN = (1<<21);      // always draw this
 static const int POLY_TRIANGLES = (1<<22);      // made of TRIANGLES, not TRIANGLE_FAN
 static const int POLY_INTENSE = (1<<23);        // extra intense colors
+static const int POLY_DEBUG = (1<<24);          // debug this shape
 
 void pregen();
 extern vector<eLand> currentlands;