diff --git a/src/builtins/shared.rs b/src/builtins/shared.rs
index f328389af..b1eefe5d1 100644
--- a/src/builtins/shared.rs
+++ b/src/builtins/shared.rs
@@ -1,5 +1,5 @@
 use super::prelude::*;
-use crate::common::{Named, bytes2wcstring, escape, get_by_sorted_name};
+use crate::common::{Named, bytes2wcstring, escape, get_by_sorted_name, str2wcstring};
 use crate::fds::BorrowedFdFile;
 use crate::io::OutputStream;
 use crate::parse_constants::UNKNOWN_BUILTIN_ERR_MSG;
@@ -716,7 +716,7 @@ pub fn builtin_wperror(program_name: &wstr, streams: &mut IoStreams) {
     streams.err.append(program_name);
     streams.err.append(L!(": "));
     if err.0 != 0 {
-        let werr = WString::from_str(&err.to_string());
+        let werr = str2wcstring(err.to_string());
         streams.err.append(&werr);
         streams.err.append_char('\n');
     }
diff --git a/src/builtins/string/match.rs b/src/builtins/string/match.rs
index 6c3067195..af1ca900f 100644
--- a/src/builtins/string/match.rs
+++ b/src/builtins/string/match.rs
@@ -3,6 +3,7 @@
 use std::num::NonZeroUsize;
 
 use super::*;
+use crate::common::str2wcstring;
 use crate::env::{EnvVar, EnvVarFlags};
 use crate::flog::flog;
 use crate::parse_util::unescape_wildcards;
@@ -307,7 +308,7 @@ fn validate_capture_group_names(
         capture_group_names: &[Option<String>],
     ) -> Result<(), RegexError> {
         for name in capture_group_names.iter().filter_map(|n| n.as_ref()) {
-            let wname = WString::from_str(name);
+            let wname = str2wcstring(name);
             if EnvVar::flags_for(&wname).contains(EnvVarFlags::READ_ONLY) {
                 return Err(RegexError::InvalidCaptureGroupName(wname));
             }
diff --git a/src/builtins/test.rs b/src/builtins/test.rs
index e06608539..f971b8cc4 100644
--- a/src/builtins/test.rs
+++ b/src/builtins/test.rs
@@ -1088,6 +1088,7 @@ pub fn test(parser: &Parser, streams: &mut IoStreams, argv: &mut [&wstr]) -> Bui
 mod tests {
     use super::test as builtin_test;
     use crate::builtins::prelude::*;
+    use crate::common::str2wcstring;
     use crate::io::{IoChain, OutputStream};
     use crate::tests::prelude::*;
 
@@ -1100,7 +1101,7 @@ fn run_one_test_test_mbracket(expected: i32, lst: &[&str], bracket: bool) -> boo
             argv.push(L!("test").to_owned());
         }
         for s in lst {
-            argv.push(WString::from_str(s));
+            argv.push(str2wcstring(s));
         }
         if bracket {
             argv.push(L!("]").to_owned())
diff --git a/src/complete.rs b/src/complete.rs
index 3d443dea3..5d8c9250e 100644
--- a/src/complete.rs
+++ b/src/complete.rs
@@ -2633,6 +2633,7 @@ mod tests {
         sort_and_prioritize,
     };
     use crate::abbrs::{self, Abbreviation, with_abbrs_mut};
+    use crate::common::str2wcstring;
     use crate::env::{EnvMode, EnvSetMode, Environment};
     use crate::io::IoChain;
     use crate::operation_context::{
@@ -3281,7 +3282,7 @@ macro_rules! perform_one_completion_cd_test {
 
         vars.parent
             .vars
-            .insert(L!("AUTOSUGGEST_TEST_LOC").to_owned(), WString::from_str(wd));
+            .insert(L!("AUTOSUGGEST_TEST_LOC").to_owned(), str2wcstring(wd));
         perform_one_autosuggestion_cd_test!("cd $AUTOSUGGEST_TEST_LOC/0", "foobar/", &vars);
         perform_one_autosuggestion_cd_test!("cd ~/test_autosuggest_suggest_specia", "l/", &vars);
 
diff --git a/src/env_universal_common.rs b/src/env_universal_common.rs
index 3f4eb1ea5..dba823ae5 100644
--- a/src/env_universal_common.rs
+++ b/src/env_universal_common.rs
@@ -248,6 +248,7 @@ fn populate_variables(s: &[u8], out_vars: &mut VarTable) -> UvarFormat {
             let Ok(line) = std::str::from_utf8(line) else {
                 continue;
             };
+            // TODO: investigate whether this should use str2wcstring
             wide_line = WString::from_str(line);
 
             match format {
diff --git a/src/event.rs b/src/event.rs
index 9f98597a6..e75fdc852 100644
--- a/src/event.rs
+++ b/src/event.rs
@@ -7,7 +7,7 @@
 use std::sync::atomic::{AtomicBool, AtomicU32, Ordering};
 use std::sync::{Arc, Mutex};
 
-use crate::common::{ScopeGuard, escape};
+use crate::common::{ScopeGuard, escape, str2wcstring};
 use crate::flog::flog;
 use crate::io::{IoChain, IoStreams};
 use crate::job_group::MaybeJobId;
@@ -402,7 +402,7 @@ pub fn get_desc(parser: &Parser, evt: &Event) -> WString {
         EventDescription::Any => unreachable!(),
     };
 
-    WString::from_str(&s)
+    str2wcstring(&s)
 }
 
 /// Add an event handler.
diff --git a/src/expand.rs b/src/expand.rs
index 4dbca809e..f60739779 100644
--- a/src/expand.rs
+++ b/src/expand.rs
@@ -1591,6 +1591,7 @@ mod tests {
     use crate::abbrs::Abbreviation;
     use crate::abbrs::{self};
     use crate::abbrs::{with_abbrs, with_abbrs_mut};
+    use crate::common::str2wcstring;
     use crate::complete::{CompletionList, CompletionReceiver};
     use crate::env::{EnvMode, EnvStackSetResult};
     use crate::expand::{ExpandResultCode, expand_to_receiver};
@@ -1953,7 +1954,7 @@ fn test_expand_overflow() {
         // Make a list of 64 elements, then expand it cartesian-style 64 times.
         // This is far too large to expand.
         let vals: Vec<WString> = (1..=64).map(|i| i.to_wstring()).collect();
-        let expansion = WString::from_str(&str::repeat("$bigvar", 64));
+        let expansion = str2wcstring(str::repeat("$bigvar", 64));
 
         let parser = TestParser::new();
         parser.vars().push(true);
diff --git a/src/highlight/file_tester.rs b/src/highlight/file_tester.rs
index 2cb103caa..cce1b87d2 100644
--- a/src/highlight/file_tester.rs
+++ b/src/highlight/file_tester.rs
@@ -426,6 +426,7 @@ pub fn fs_is_case_insensitive(
 #[cfg(test)]
 mod tests {
     use super::{FileTester, IsErr, IsFile, PathFlags, is_potential_path};
+    use crate::common::osstr2wcstring;
     use crate::env::EnvStack;
     use crate::operation_context::{EXPANSION_LIMIT_DEFAULT, OperationContext};
     use crate::prelude::*;
@@ -454,10 +455,7 @@ fn filepath(&self, name: &str) -> PathBuf {
         }
 
         fn file_tester(&self) -> FileTester<'_> {
-            FileTester::new(
-                WString::from_str(self.tempdir.path().to_str().unwrap()),
-                &self.ctx,
-            )
+            FileTester::new(osstr2wcstring(self.tempdir.path()), &self.ctx)
         }
     }
 
diff --git a/src/localization/gettext.rs b/src/localization/gettext.rs
index 4c3e24388..bccc295e1 100644
--- a/src/localization/gettext.rs
+++ b/src/localization/gettext.rs
@@ -41,8 +41,9 @@ fn gettext(message: MaybeStatic) -> &'static wstr {
                 LazyLock::new(|| Mutex::new(HashMap::default()));
             let mut localizations_to_wide = LOCALIZATION_TO_WIDE.lock().unwrap();
             if !localizations_to_wide.contains_key(localized_str) {
-                let localization_wstr =
-                    Box::leak(WString::from_str(localized_str).into_boxed_utfstr());
+                use crate::common::str2wcstring;
+
+                let localization_wstr = Box::leak(str2wcstring(localized_str).into_boxed_utfstr());
                 localizations_to_wide.insert(localized_str, localization_wstr);
             }
             return localizations_to_wide.get(localized_str).unwrap();
diff --git a/src/localization/settings.rs b/src/localization/settings.rs
index 35bb116ae..ec7aad4c8 100644
--- a/src/localization/settings.rs
+++ b/src/localization/settings.rs
@@ -88,6 +88,10 @@ fn append_space_separated_list<S: AsRef<str>>(
     for lang in list {
         string.push(' ');
         string.push_utfstr(&crate::common::escape(
+            // lang is already PUA-encoded at this point. The reason we convert the PUA-encoded
+            // WString into a String is to enable comparison with the language names we have
+            // available. We could use WString for lang, but that would require converting our
+            // stored languages names as WString as well.
             WString::from_str(lang.as_ref()).as_utfstr(),
         ));
     }
diff --git a/src/parser.rs b/src/parser.rs
index 71680e7ca..c2a30adca 100644
--- a/src/parser.rs
+++ b/src/parser.rs
@@ -1487,6 +1487,7 @@ mod tests {
     use crate::ast::{
         self, Ast, Castable, JobList, JobPipeline, Kind, Node, Traversal, is_same_node,
     };
+    use crate::common::str2wcstring;
     use crate::env::EnvStack;
     use crate::expand::ExpandFlags;
     use crate::io::{IoBufferfill, IoChain};
@@ -1513,7 +1514,7 @@ macro_rules! detect_errors {
         }
 
         fn detect_argument_errors(src: &str) -> Result<(), ParserTestErrorBits> {
-            let src = WString::from_str(src);
+            let src = str2wcstring(src);
             let ast = ast::parse_argument_list(&src, ParseTreeFlags::default(), None);
             if ast.errored() {
                 return Err(ParserTestErrorBits::ERROR);