diff --git a/src/lua_maplib.c b/src/lua_maplib.c
index 23a293d6b..9e58f4b6b 100644
--- a/src/lua_maplib.c
+++ b/src/lua_maplib.c
@@ -88,6 +88,7 @@ enum line_e {
 	line_v2,
 	line_dx,
 	line_dy,
+	line_angle,
 	line_flags,
 	line_special,
 	line_tag,
@@ -113,6 +114,7 @@ static const char *const line_opt[] = {
 	"v2",
 	"dx",
 	"dy",
+	"angle",
 	"flags",
 	"special",
 	"tag",
@@ -823,6 +825,9 @@ static int line_get(lua_State *L)
 	case line_dy:
 		lua_pushfixed(L, line->dy);
 		return 1;
+	case line_angle:
+		lua_pushangle(L, line->angle);
+		return 1;
 	case line_flags:
 		lua_pushinteger(L, line->flags);
 		return 1;
diff --git a/src/p_map.c b/src/p_map.c
index 8cd0223d0..9f80d92b5 100644
--- a/src/p_map.c
+++ b/src/p_map.c
@@ -3101,7 +3101,7 @@ static void P_HitCameraSlideLine(line_t *ld, camera_t *thiscam)
 	}
 
 	side = P_PointOnLineSide(thiscam->x, thiscam->y, ld);
-	lineangle = R_PointToAngle2(0, 0, ld->dx, ld->dy);
+	lineangle = ld->angle;
 
 	if (side == 1)
 		lineangle += ANGLE_180;
@@ -3147,7 +3147,7 @@ static void P_HitSlideLine(line_t *ld)
 
 	side = P_PointOnLineSide(slidemo->x, slidemo->y, ld);
 
-	lineangle = R_PointToAngle2(0, 0, ld->dx, ld->dy);
+	lineangle = ld->angle;
 
 	if (side == 1)
 		lineangle += ANGLE_180;
@@ -3190,7 +3190,7 @@ static void P_HitBounceLine(line_t *ld)
 		return;
 	}
 
-	lineangle = R_PointToAngle2(0, 0, ld->dx, ld->dy);
+	lineangle = ld->angle;
 
 	if (lineangle >= ANGLE_180)
 		lineangle -= ANGLE_180;
diff --git a/src/p_polyobj.c b/src/p_polyobj.c
index 0ccb6ebde..6d7ef3999 100644
--- a/src/p_polyobj.c
+++ b/src/p_polyobj.c
@@ -785,7 +785,7 @@ static void Polyobj_pushThing(polyobj_t *po, line_t *line, mobj_t *mo)
 	vertex_t closest;
 
 	// calculate angle of line and subtract 90 degrees to get normal
-	lineangle = R_PointToAngle2(0, 0, line->dx, line->dy) - ANGLE_90;
+	lineangle = line->angle - ANGLE_90;
 	lineangle >>= ANGLETOFINESHIFT;
 	momx = FixedMul(po->thrust, FINECOSINE(lineangle));
 	momy = FixedMul(po->thrust, FINESINE(lineangle));
@@ -1060,6 +1060,8 @@ static void Polyobj_rotateLine(line_t *ld)
 	ld->dx = v2->x - v1->x;
 	ld->dy = v2->y - v1->y;
 
+	ld->angle = R_PointToAngle2(0, 0, ld->dx, ld->dy);
+
 	// determine slopetype
 	ld->slopetype = !ld->dx ? ST_VERTICAL : !ld->dy ? ST_HORIZONTAL :
 			((ld->dy > 0) == (ld->dx > 0)) ? ST_POSITIVE : ST_NEGATIVE;
diff --git a/src/p_setup.c b/src/p_setup.c
index a828a590e..b4675b27d 100644
--- a/src/p_setup.c
+++ b/src/p_setup.c
@@ -1069,6 +1069,8 @@ static void P_InitializeLinedef(line_t *ld)
 	ld->dx = v2->x - v1->x;
 	ld->dy = v2->y - v1->y;
 
+	ld->angle = R_PointToAngle2(0, 0, ld->dx, ld->dy);
+
 	ld->bbox[BOXLEFT] = min(v1->x, v2->x);
 	ld->bbox[BOXRIGHT] = max(v1->x, v2->x);
 	ld->bbox[BOXBOTTOM] = min(v1->y, v2->y);
diff --git a/src/p_spec.c b/src/p_spec.c
index fa590b5cb..3fe77d7a2 100644
--- a/src/p_spec.c
+++ b/src/p_spec.c
@@ -1241,7 +1241,7 @@ static boolean PolyFlag(line_t *line)
 
 	pfd.polyObjNum = Tag_FGet(&line->tags);
 	pfd.speed = P_AproxDistance(line->dx, line->dy) >> FRACBITS;
-	pfd.angle = R_PointToAngle2(line->v1->x, line->v1->y, line->v2->x, line->v2->y) >> ANGLETOFINESHIFT;
+	pfd.angle = line->angle >> ANGLETOFINESHIFT;
 	pfd.momx = sides[line->sidenum[0]].textureoffset >> FRACBITS;
 
 	return EV_DoPolyObjFlag(&pfd);
diff --git a/src/r_defs.h b/src/r_defs.h
index c6467a970..b72d3ddd8 100644
--- a/src/r_defs.h
+++ b/src/r_defs.h
@@ -387,6 +387,7 @@ typedef struct line_s
 	vertex_t *v2;
 
 	fixed_t dx, dy; // Precalculated v2 - v1 for side checking.
+	angle_t angle; // Precalculated angle between dx and dy
 
 	// Animation related.
 	INT16 flags;