diff --git a/src/cvars.cpp b/src/cvars.cpp
index fd93e79f8..b16d04987 100644
--- a/src/cvars.cpp
+++ b/src/cvars.cpp
@@ -878,6 +878,7 @@ consvar_t cv_debugrank = PlayerCheat("debugrank", "Off").description("Show GP ra
 consvar_t cv_debugrender_contrast = PlayerCheat("debugrender_contrast", "0.0").floating_point().min_max(-FRACUNIT, FRACUNIT).description("Change level lighting");
 consvar_t cv_debugrender_portal = PlayerCheat("debugrender_portal", "Off").on_off().description("Highlight visual portals in red");
 consvar_t cv_debugrender_spriteclip = PlayerCheat("debugrender_spriteclip", "Off").on_off().description("Let sprites draw through walls");
+consvar_t cv_debugrender_visplanes = PlayerCheat("debugrender_visplanes", "Off").on_off().description("Highlight the number of visplanes");
 consvar_t cv_devmode_screen = PlayerCheat("devmode_screen", "1").min_max(1, 4).description("Choose which splitscreen player devmode applies to");
 consvar_t cv_drawpickups = PlayerCheat("drawpickups", "Yes").yes_no().description("Hide rings, spheres, item capsules, prison capsules (visual only)");
 consvar_t cv_drawinput = PlayerCheat("drawinput", "No").yes_no().description("Draw turn inputs outside of Record Attack (turn solver debugging)");
diff --git a/src/r_main.cpp b/src/r_main.cpp
index 7277c2ace..2649fb3a1 100644
--- a/src/r_main.cpp
+++ b/src/r_main.cpp
@@ -55,6 +55,8 @@ INT64 mytotal = 0;
 #endif
 //profile stuff ---------------------------------------------------------
 
+extern "C" consvar_t cv_debugrender_visplanes;
+
 // Fineangles in the SCREENWIDTH wide window.
 #define FIELDOFVIEW 2048
 
@@ -1603,6 +1605,58 @@ void R_RenderPlayerView(void)
 	R_DrawMasked(masks, nummasks);
 	ps_sw_maskedtime = I_GetPreciseTime() - ps_sw_maskedtime;
 
+	if (cv_debugrender_visplanes.value)
+	{
+		for (INT32 i = 0; i < MAXVISPLANES; i++)
+		{
+			for (visplane_t* pl = visplanes[i]; pl; pl = pl->next)
+			{
+				if (pl->minx > pl->maxx)
+					continue;
+				auto col = [](int x, int top, int bot)
+				{
+					if (top > bot)
+						std::swap(top, bot);
+					UINT8* p = &screens[0][x + top * vid.width];
+					while (top <= bot)
+					{
+						*p = 35;
+						p += vid.width;
+						top++;
+					}
+				};
+				auto span = [col](int x, int top, int bot)
+				{
+					if (top <= bot)
+						col(x, top, bot);
+				};
+				INT32 top = pl->top[pl->minx];
+				INT32 bottom = pl->bottom[pl->minx];
+				span(pl->minx, top, bottom);
+				span(pl->maxx, pl->top[pl->maxx], pl->bottom[pl->maxx]);
+				for (INT32 x = pl->minx + 1; x < pl->maxx; ++x)
+				{
+					INT32 new_top = pl->top[x];
+					INT32 new_bottom = pl->bottom[x];
+					if (new_top > new_bottom)
+						continue;
+					if (top > bottom)
+					{
+						col(x, new_top, new_top);
+						col(x, new_bottom, new_bottom);
+					}
+					else
+					{
+						col(x, top, new_top);
+						col(x, bottom, new_bottom);
+					}
+					top = new_top;
+					bottom = new_bottom;
+				}
+			}
+		}
+	}
+
 	// debugrender_portal: fill portals with red, draw over everything
 	if (portal_base && cv_debugrender_portal.value)
 	{