diff --git a/src/__private__/__half_trapezium.scad b/src/__private__/__half_trapezium.scad
index 28c352c0..234a3ab9 100644
--- a/src/__private__/__half_trapezium.scad
+++ b/src/__private__/__half_trapezium.scad
@@ -1,7 +1,7 @@
 function __half_trapezium(radius, h, round_r) =
     let(
         is_vt = __is_vector(radius),
-        r1 = is_vt ? radius[0] : radiusm,
+        r1 = is_vt ? radius[0] : radius,
         r2 = is_vt ? radius[1] : radius,
         frags = __frags(round_r),
         b_ang = atan2(h, r1 - r2),
diff --git a/src/__private__/__trapezium.scad b/src/__private__/__trapezium.scad
new file mode 100644
index 00000000..e48cf14b
--- /dev/null
+++ b/src/__private__/__trapezium.scad
@@ -0,0 +1,14 @@
+function __trapezium(radius, h, round_r) =
+    let(
+        r_half_trapezium = __half_trapezium(radius, h, round_r),
+        to = len(r_half_trapezium) - 1,
+        l_half_trapezium = [
+            for(i = [0:to]) 
+                let(pt = r_half_trapezium[to - i])
+                [-pt[0], pt[1]]
+        ]
+    )    
+    concat(
+        r_half_trapezium,
+        l_half_trapezium
+    );
\ No newline at end of file
diff --git a/src/shape_square.scad b/src/shape_square.scad
index e83eb596..c0269ca5 100644
--- a/src/shape_square.scad
+++ b/src/shape_square.scad
@@ -15,33 +15,17 @@
 include <__private__/__is_vector.scad>;
 include <__private__/__frags.scad>;
 include <__private__/__pie_for_rounding.scad>;
+include <__private__/__half_trapezium.scad>;
+include <__private__/__trapezium.scad>;
 
 function shape_square(size, corner_r = 0) = 
     let(
-        corner_frags = __frags(corner_r) / 4,
         x = __is_vector(size) ? size[0] : size,
-        y = __is_vector(size) ? size[1] : size,
-        half_x = x / 2,
-        half_y = y / 2, 
-        half_w = half_x - corner_r,
-        half_h = half_y - corner_r,
-        right_side = [
-            for(pt = __pie_for_rounding(corner_r, -90, 0, corner_frags)) 
-                [pt[0] + half_w - corner_r,  pt[1] - half_h + corner_r]
-        ],        
-        top_side = [
-            for(pt = __pie_for_rounding(corner_r, 0, 90, corner_frags)) 
-                [pt[0] + half_w - corner_r,  pt[1] + half_h - corner_r]
-        ],
-        left_side = [
-            for(pt = __pie_for_rounding(corner_r, 90, 180, corner_frags)) 
-                [pt[0] - half_w + corner_r,  pt[1] + half_h - corner_r]
-        ],
-        bottom_side = [
-            for(pt = __pie_for_rounding(corner_r, 180, 270, corner_frags)) 
-                [pt[0] - half_w + corner_r,  pt[1] - half_h + corner_r]
-        ],
-        shape_pts = concat(
-            right_side, top_side, left_side, bottom_side
-        )
-    ) shape_pts;
\ No newline at end of file
+        y = __is_vector(size) ? size[1] : size        
+    )
+    __trapezium(
+        radius = x, 
+        h = y, 
+        round_r = corner_r
+    );
+    
\ No newline at end of file