diff --git a/helix-stdx/src/env.rs b/helix-stdx/src/env.rs
index 6e14c7a875ae9..bef2976895032 100644
--- a/helix-stdx/src/env.rs
+++ b/helix-stdx/src/env.rs
@@ -103,6 +103,12 @@ fn expand_impl(src: &OsStr, mut resolve: impl FnMut(&OsStr) -> Option<OsString>)
         let mat = captures.get_match().unwrap();
         let pattern_id = mat.pattern().as_usize();
         let mut range = mat.range();
+        // A pattern may match multiple times on a single variable, for example `${HOME:-$HOME}`:
+        // `${HOME:-` matches and also the default value (`$HOME`). Skip past any variables which
+        // have already been expanded.
+        if range.start < pos {
+            continue;
+        }
         let var = &bytes[captures.get_group(1).unwrap().range()];
         let default = if pattern_id != 5 {
             let Some(bracket_pos) = find_brace_end(&bytes[range.end..]) else {