diff --git a/src/std/math/matrix.nt b/src/std/math/matrix.nt
index d4e6fc66..29676675 100644
--- a/src/std/math/matrix.nt
+++ b/src/std/math/matrix.nt
@@ -112,10 +112,10 @@ struct mat4x4 {
     }
 
     /// Create an orthogonal projection matrix.
-    static mat4x4 ortho(float left, float right, float bottom, float top, float near, float far) {
-        float dx = right - left, dy = top - bottom, dz = far - near;
+    static mat4x4 ortho(float left, float right, float bottom_, float top, float near, float far) {
+        float dx = right - left, dy = top - bottom_, dz = far - near;
         float tx = -(right + left) / dx;
-        float ty = -(top + bottom) / dy;
+        float ty = -(top + bottom_) / dy;
         float tz = -(far + near) / dz;
         return mat4x4(
             vec4f(2/dx,    0,     0, tx),