diff --git a/render.c b/render.c
index 942653b4..6918797c 100644
--- a/render.c
+++ b/render.c
@@ -22,7 +22,7 @@
 #define max(x, y) ((x) > (y) ? (x) : (y))
 
 struct font *
-attrs_to_font(struct terminal *term, const struct attributes *attrs)
+attrs_to_font(const struct terminal *term, const struct attributes *attrs)
 {
     int idx = attrs->italic << 1 | attrs->bold;
     return term->fonts[idx];
diff --git a/render.h b/render.h
index 1c6bbd7f..ad6b6578 100644
--- a/render.h
+++ b/render.h
@@ -3,7 +3,7 @@
 #include "terminal.h"
 
 struct font *attrs_to_font(
-    struct terminal *term, const struct attributes *attrs);
+    const struct terminal *term, const struct attributes *attrs);
 
 void grid_render(struct terminal *term);
 void render_resize(struct terminal *term, int width, int height);