diff --git a/lib/smol_str/src/lib.rs b/lib/smol_str/src/lib.rs
index 45f1cb2542..7314d270f3 100644
--- a/lib/smol_str/src/lib.rs
+++ b/lib/smol_str/src/lib.rs
@@ -1,4 +1,10 @@
-use std::{borrow::Borrow, cmp::Ordering, fmt, hash, iter, ops::Deref, sync::Arc};
+use std::{
+    borrow::Borrow,
+    cmp::{self, Ordering},
+    fmt, hash, iter,
+    ops::Deref,
+    sync::Arc,
+};
 
 /// A `SmolStr` is a string type that has the following properties:
 ///
@@ -358,10 +364,17 @@ impl Repr {
                 };
             }
 
-            let newlines = text.bytes().take_while(|&b| b == b'\n').count();
-            if text[newlines..].bytes().all(|b| b == b' ') {
-                let spaces = len - newlines;
-                if newlines <= N_NEWLINES && spaces <= N_SPACES {
+            if len <= N_NEWLINES + N_SPACES {
+                let bytes = text.as_bytes();
+                let possible_newline_count = cmp::min(len, N_NEWLINES);
+                let newlines = bytes[..possible_newline_count]
+                    .iter()
+                    .take_while(|&&b| b == b'\n')
+                    .count();
+                let possible_space_count = len - newlines;
+                if possible_space_count <= N_SPACES && bytes[newlines..].iter().all(|&b| b == b' ')
+                {
+                    let spaces = possible_space_count;
                     return Repr::Substring { newlines, spaces };
                 }
             }