diff --git a/crates/fallback/src/lib.rs b/crates/fallback/src/lib.rs
index 822c4ee4b..5c74cdbc7 100644
--- a/crates/fallback/src/lib.rs
+++ b/crates/fallback/src/lib.rs
@@ -63,15 +63,19 @@ pub fn fish_wcwidth(c: char) -> isize {
     }
 }
 
-/// fish's internal versions of wcwidth and wcswidth
 pub fn fish_wcswidth(s: &wstr) -> isize {
-    // ascii fast path; empty iterator returns true for .all()
-    if s.chars().all(|c| c.is_ascii() && !c.is_ascii_control()) {
+    fish_wcswidth_canonicalizing(s, std::convert::identity)
+}
+
+pub fn fish_wcswidth_canonicalizing(s: &wstr, canonicalize: fn(char) -> char) -> isize {
+    // ascii fast path
+    let chars = s.chars().map(canonicalize);
+    if chars.clone().all(|c| c.is_ascii() && !c.is_ascii_control()) {
         return s.len() as isize;
     }
 
     let mut result = 0;
-    for c in s.chars() {
+    for c in chars {
         let w = fish_wcwidth(c);
         if w < 0 {
             return -1;
diff --git a/src/pager.rs b/src/pager.rs
index 7dd742587..3535d96db 100644
--- a/src/pager.rs
+++ b/src/pager.rs
@@ -358,17 +358,14 @@ fn measure_completion_infos(&mut self) {
                     comp.comp_width += 2;
                 }
 
-                // This can return -1 if it can't calculate the width. So be cautious.
-                let comp_width = wcswidth_rendered(comp_string);
                 if show_prefix {
-                    comp.comp_width += usize::try_from(prefix_len).unwrap_or_default();
+                    comp.comp_width += prefix_len;
                 }
-                comp.comp_width += usize::try_from(comp_width).unwrap_or_default();
+                comp.comp_width += wcswidth_rendered(comp_string);
             }
 
             // This can return -1 if it can't calculate the width. So be cautious.
-            let desc_width = wcswidth_rendered(&comp.desc);
-            comp.desc_width = usize::try_from(desc_width).unwrap_or_default();
+            comp.desc_width = wcswidth_rendered(&comp.desc);
         }
     }
 
diff --git a/src/screen.rs b/src/screen.rs
index 051c55fd1..8a38f188a 100644
--- a/src/screen.rs
+++ b/src/screen.rs
@@ -24,7 +24,7 @@
 use crate::terminal::{BufferedOutputter, CardinalDirection, Outputter};
 use crate::termsize::Termsize;
 use crate::wutil::fstat;
-use fish_fallback::fish_wcwidth;
+use fish_fallback::{fish_wcswidth_canonicalizing, fish_wcwidth};
 use fish_wcstringutil::{fish_wcwidth_visible, string_prefixes_string, wcs2bytes};
 use fish_widestring::ELLIPSIS_CHAR;
 use libc::{STDERR_FILENO, STDOUT_FILENO};
@@ -2065,8 +2065,11 @@ fn wcwidth_rendered_min_0(c: char) -> usize {
 pub fn wcwidth_rendered(c: char) -> isize {
     fish_wcwidth(rendered_character(c))
 }
-pub fn wcswidth_rendered(s: &wstr) -> isize {
-    s.chars().map(wcwidth_rendered).sum()
+pub fn wcswidth_rendered(s: &wstr) -> usize {
+    fish_wcswidth_canonicalizing(s, rendered_character)
+        .max(0)
+        .try_into()
+        .unwrap()
 }
 
 #[cfg(test)]