diff --git a/src/fish_tests.cpp b/src/fish_tests.cpp
index ebaa42f2c..7c20ff49c 100644
--- a/src/fish_tests.cpp
+++ b/src/fish_tests.cpp
@@ -1875,54 +1875,48 @@ static void test_abbreviations() {
     if (!mresult) err(L"Unexpected failure with foo abbreviation");
     if (*mresult != L"bar") err(L"Wrong abbreviation result for foo");
 
-    bool expanded;
-    wcstring result;
-    expanded = reader_expand_abbreviation_in_command(L"just a command", 3, vars, &result);
-    if (expanded) err(L"Command wrongly expanded on line %ld", (long)__LINE__);
-    expanded = reader_expand_abbreviation_in_command(L"gc somebranch", 0, vars, &result);
-    if (!expanded) err(L"Command not expanded on line %ld", (long)__LINE__);
+    maybe_t<wcstring> result;
+    result = reader_expand_abbreviation_in_command(L"just a command", 3, vars);
+    if (result) err(L"Command wrongly expanded on line %ld", (long)__LINE__);
+    result = reader_expand_abbreviation_in_command(L"gc somebranch", 0, vars);
+    if (!result) err(L"Command not expanded on line %ld", (long)__LINE__);
 
-    expanded =
-        reader_expand_abbreviation_in_command(L"gc somebranch", std::wcslen(L"gc"), vars, &result);
-    if (!expanded) err(L"gc not expanded");
+    result = reader_expand_abbreviation_in_command(L"gc somebranch", std::wcslen(L"gc"), vars);
+    if (!result) err(L"gc not expanded");
     if (result != L"git checkout somebranch")
-        err(L"gc incorrectly expanded on line %ld to '%ls'", (long)__LINE__, result.c_str());
+        err(L"gc incorrectly expanded on line %ld to '%ls'", (long)__LINE__, result->c_str());
 
     // Space separation.
-    expanded =
-        reader_expand_abbreviation_in_command(L"gx somebranch", std::wcslen(L"gc"), vars, &result);
-    if (!expanded) err(L"gx not expanded");
+    result = reader_expand_abbreviation_in_command(L"gx somebranch", std::wcslen(L"gc"), vars);
+    if (!result) err(L"gx not expanded");
     if (result != L"git checkout somebranch")
-        err(L"gc incorrectly expanded on line %ld to '%ls'", (long)__LINE__, result.c_str());
+        err(L"gc incorrectly expanded on line %ld to '%ls'", (long)__LINE__, result->c_str());
 
-    expanded = reader_expand_abbreviation_in_command(L"echo hi ; gc somebranch",
-                                                     std::wcslen(L"echo hi ; g"), vars, &result);
-    if (!expanded) err(L"gc not expanded on line %ld", (long)__LINE__);
+    result = reader_expand_abbreviation_in_command(L"echo hi ; gc somebranch",
+                                                   std::wcslen(L"echo hi ; g"), vars);
+    if (!result) err(L"gc not expanded on line %ld", (long)__LINE__);
     if (result != L"echo hi ; git checkout somebranch")
         err(L"gc incorrectly expanded on line %ld", (long)__LINE__);
 
-    expanded = reader_expand_abbreviation_in_command(
-        L"echo (echo (echo (echo (gc ", std::wcslen(L"echo (echo (echo (echo (gc"), vars, &result);
-    if (!expanded) err(L"gc not expanded on line %ld", (long)__LINE__);
+    result = reader_expand_abbreviation_in_command(
+        L"echo (echo (echo (echo (gc ", std::wcslen(L"echo (echo (echo (echo (gc"), vars);
+    if (!result) err(L"gc not expanded on line %ld", (long)__LINE__);
     if (result != L"echo (echo (echo (echo (git checkout ")
-        err(L"gc incorrectly expanded on line %ld to '%ls'", (long)__LINE__, result.c_str());
+        err(L"gc incorrectly expanded on line %ld to '%ls'", (long)__LINE__, result->c_str());
 
     // If commands should be expanded.
-    expanded =
-        reader_expand_abbreviation_in_command(L"if gc", std::wcslen(L"if gc"), vars, &result);
-    if (!expanded) err(L"gc not expanded on line %ld", (long)__LINE__);
+    result = reader_expand_abbreviation_in_command(L"if gc", std::wcslen(L"if gc"), vars);
+    if (!result) err(L"gc not expanded on line %ld", (long)__LINE__);
     if (result != L"if git checkout")
-        err(L"gc incorrectly expanded on line %ld to '%ls'", (long)__LINE__, result.c_str());
+        err(L"gc incorrectly expanded on line %ld to '%ls'", (long)__LINE__, result->c_str());
 
     // Others should not be.
-    expanded =
-        reader_expand_abbreviation_in_command(L"of gc", std::wcslen(L"of gc"), vars, &result);
-    if (expanded) err(L"gc incorrectly expanded on line %ld", (long)__LINE__);
+    result = reader_expand_abbreviation_in_command(L"of gc", std::wcslen(L"of gc"), vars);
+    if (result) err(L"gc incorrectly expanded on line %ld", (long)__LINE__);
 
     // Others should not be.
-    expanded = reader_expand_abbreviation_in_command(L"command gc", std::wcslen(L"command gc"),
-                                                     vars, &result);
-    if (expanded) err(L"gc incorrectly expanded on line %ld", (long)__LINE__);
+    result = reader_expand_abbreviation_in_command(L"command gc", std::wcslen(L"command gc"), vars);
+    if (result) err(L"gc incorrectly expanded on line %ld", (long)__LINE__);
 
     vars.pop();
 }
diff --git a/src/reader.cpp b/src/reader.cpp
index 37eca2b7b..7efe0d929 100644
--- a/src/reader.cpp
+++ b/src/reader.cpp
@@ -729,8 +729,8 @@ void reader_data_t::pager_selection_changed() {
 }
 
 /// Expand abbreviations at the given cursor position. Does NOT inspect 'data'.
-bool reader_expand_abbreviation_in_command(const wcstring &cmdline, size_t cursor_pos,
-                                           const environment_t &vars, wcstring *output) {
+maybe_t<wcstring> reader_expand_abbreviation_in_command(const wcstring &cmdline, size_t cursor_pos,
+                                                        const environment_t &vars) {
     // See if we are at "command position". Get the surrounding command substitution, and get the
     // extent of the first token.
     const wchar_t *const buff = cmdline.c_str();
@@ -778,18 +778,16 @@ bool reader_expand_abbreviation_in_command(const wcstring &cmdline, size_t curso
     }
 
     // Now if we found a command node, expand it.
-    bool result = false;
+    maybe_t<wcstring> result{};
     if (matching_cmd_node) {
         const wcstring token = matching_cmd_node.get_source(subcmd);
         if (auto abbreviation = expand_abbreviation(token, vars)) {
             // There was an abbreviation! Replace the token in the full command. Maintain the
             // relative position of the cursor.
-            if (output != NULL) {
-                output->assign(cmdline);
-                source_range_t r = *matching_cmd_node.source_range();
-                output->replace(subcmd_offset + r.start, r.length, *abbreviation);
-            }
-            result = true;
+            wcstring output = cmdline;
+            source_range_t r = *matching_cmd_node.source_range();
+            output.replace(subcmd_offset + r.start, r.length, *abbreviation);
+            result = std::move(output);
         }
     }
     return result;
@@ -804,15 +802,15 @@ bool reader_data_t::expand_abbreviation_as_necessary(size_t cursor_backtrack) {
 
     if (expand_abbreviations && el == &command_line) {
         // Try expanding abbreviations.
-        wcstring new_cmdline;
         size_t cursor_pos = el->position - std::min(el->position, cursor_backtrack);
 
-        if (reader_expand_abbreviation_in_command(el->text, cursor_pos, vars(), &new_cmdline)) {
+        if (auto new_cmdline =
+                reader_expand_abbreviation_in_command(el->text, cursor_pos, vars())) {
             // We expanded an abbreviation! The cursor moves by the difference in the command line
             // lengths.
-            size_t new_buff_pos = el->position + new_cmdline.size() - el->text.size();
+            size_t new_buff_pos = el->position + new_cmdline->size() - el->text.size();
 
-            el->text = std::move(new_cmdline);
+            el->text = std::move(*new_cmdline);
             update_buff_pos(el, new_buff_pos);
             command_line_changed(el);
             result = true;
diff --git a/src/reader.h b/src/reader.h
index efd768304..76d7a6137 100644
--- a/src/reader.h
+++ b/src/reader.h
@@ -216,8 +216,9 @@ wcstring combine_command_and_autosuggestion(const wcstring &cmdline,
                                             const wcstring &autosuggestion);
 
 /// Expand abbreviations at the given cursor position. Exposed for testing purposes only.
-bool reader_expand_abbreviation_in_command(const wcstring &cmdline, size_t cursor_pos,
-                                           const environment_t &vars, wcstring *output);
+/// \return none if no abbreviations were expanded, otherwise the new command line.
+maybe_t<wcstring> reader_expand_abbreviation_in_command(const wcstring &cmdline, size_t cursor_pos,
+                                                        const environment_t &vars);
 
 /// Apply a completion string. Exposed for testing only.
 wcstring completion_apply_to_command_line(const wcstring &val_str, complete_flags_t flags,