diff --git a/src/parse_tree.cpp b/src/parse_tree.cpp
index f07102d87..a98971602 100644
--- a/src/parse_tree.cpp
+++ b/src/parse_tree.cpp
@@ -1073,26 +1073,6 @@ static inline bool is_help_argument(const wcstring &txt) {
     return txt == L"-h" || txt == L"--help";
 }
 
-// Return the location of the equals sign, or npos if the string does
-// not look like a variable assignment like FOO=bar.  The detection
-// works similar as in some POSIX shells: only letters and numbers qre
-// allowed on the left hand side, no quotes or escaping.
-maybe_t<size_t> variable_assignment_equals_pos(const wcstring &txt) {
-    enum { init, has_some_variable_identifier } state = init;
-    // TODO bracket indexing
-    for (size_t i = 0; i < txt.size(); i++) {
-        wchar_t c = txt[i];
-        if (state == init) {
-            if (!valid_var_name_char(c)) return {};
-            state = has_some_variable_identifier;
-        } else {
-            if (c == '=') return {i};
-            if (!valid_var_name_char(c)) return {};
-        }
-    }
-    return {};
-}
-
 /// Return a new parse token, advancing the tokenizer.
 static inline parse_token_t next_parse_token(tokenizer_t *tok, maybe_t<tok_t> *out_token,
                                              wcstring *storage) {
diff --git a/src/parse_tree.h b/src/parse_tree.h
index d1f60834d..bd228590c 100644
--- a/src/parse_tree.h
+++ b/src/parse_tree.h
@@ -235,9 +235,6 @@ using parsed_source_ref_t = std::shared_ptr<const parsed_source_t>;
 parsed_source_ref_t parse_source(wcstring src, parse_tree_flags_t flags, parse_error_list_t *errors,
                                  parse_token_type_t goal = symbol_job_list);
 
-/// The position of the equal sign in a variable assignment like foo=bar.
-maybe_t<size_t> variable_assignment_equals_pos(const wcstring &txt);
-
 /// Error message for improper use of the exec builtin.
 #define EXEC_ERR_MSG _(L"The '%ls' command can not be used in a pipeline")
 
diff --git a/src/tokenizer.cpp b/src/tokenizer.cpp
index 51d48a105..d2f3d7760 100644
--- a/src/tokenizer.cpp
+++ b/src/tokenizer.cpp
@@ -851,3 +851,23 @@ move_word_state_machine_t::move_word_state_machine_t(move_word_style_t syl)
     : state(0), style(syl) {}
 
 void move_word_state_machine_t::reset() { state = 0; }
+
+// Return the location of the equals sign, or npos if the string does
+// not look like a variable assignment like FOO=bar.  The detection
+// works similar as in some POSIX shells: only letters and numbers qre
+// allowed on the left hand side, no quotes or escaping.
+maybe_t<size_t> variable_assignment_equals_pos(const wcstring &txt) {
+    enum { init, has_some_variable_identifier } state = init;
+    // TODO bracket indexing
+    for (size_t i = 0; i < txt.size(); i++) {
+        wchar_t c = txt[i];
+        if (state == init) {
+            if (!valid_var_name_char(c)) return {};
+            state = has_some_variable_identifier;
+        } else {
+            if (c == '=') return {i};
+            if (!valid_var_name_char(c)) return {};
+        }
+    }
+    return {};
+}
diff --git a/src/tokenizer.h b/src/tokenizer.h
index 90563b701..a588c2ca6 100644
--- a/src/tokenizer.h
+++ b/src/tokenizer.h
@@ -210,4 +210,7 @@ class move_word_state_machine_t {
     void reset();
 };
 
+/// The position of the equal sign in a variable assignment like foo=bar.
+maybe_t<size_t> variable_assignment_equals_pos(const wcstring &txt);
+
 #endif