diff --git a/src/buffer/mod.rs b/src/buffer/mod.rs
index 64df487..663afc1 100644
--- a/src/buffer/mod.rs
+++ b/src/buffer/mod.rs
@@ -320,7 +320,7 @@ impl Buffer {
             let l_start = self.text.line_to_char(pos.0);
             let l_end = self.text.line_to_char(pos.0 + 1);
             return (l_start + pos.1)
-                .min(l_start.max(l_end - 1))
+                .min(l_start.max(l_end - 1.min(l_end)))
                 .min(self.text.len_chars());
         } else {
             return self.text.len_chars();
diff --git a/src/formatter.rs b/src/formatter.rs
index 636aed3..7b4fecd 100644
--- a/src/formatter.rs
+++ b/src/formatter.rs
@@ -7,7 +7,7 @@ use buffer::Buffer;
 // This is necessary to prevent pathological formatting cases which
 // could slow down the editor arbitrarily for arbitrarily long
 // lines.
-pub const LINE_BLOCK_LENGTH: usize = 4096;
+pub const LINE_BLOCK_LENGTH: usize = 1 << 12;
 
 #[derive(Copy, Clone, PartialEq)]
 pub enum RoundingBehavior {
diff --git a/src/term_ui/screen.rs b/src/term_ui/screen.rs
index 0929f81..d647f8e 100644
--- a/src/term_ui/screen.rs
+++ b/src/term_ui/screen.rs
@@ -89,16 +89,22 @@ impl Screen {
     }
 
     pub(crate) fn draw(&self, x: usize, y: usize, text: &str, style: Style) {
-        let mut buf = self.buf.borrow_mut();
-        let mut x = x;
-        for g in UnicodeSegmentation::graphemes(text, true) {
-            let width = UnicodeWidthStr::width(g);
-            if width > 0 {
-                buf[y * self.w + x] = Some((style, g.into()));
-                x += 1;
-                for _ in 0..(width - 1) {
-                    buf[y * self.w + x] = None;
+        if y < self.h {
+            let mut buf = self.buf.borrow_mut();
+            let mut x = x;
+            for g in UnicodeSegmentation::graphemes(text, true) {
+                let width = UnicodeWidthStr::width(g);
+                if width > 0 {
+                    if x < self.w {
+                        buf[y * self.w + x] = Some((style, g.into()));
+                    }
                     x += 1;
+                    for _ in 0..(width - 1) {
+                        if x < self.w {
+                            buf[y * self.w + x] = None;
+                        }
+                        x += 1;
+                    }
                 }
             }
         }