diff --git a/src/parser.cpp b/src/parser.cpp
index a8e69db35..3b25bb173 100644
--- a/src/parser.cpp
+++ b/src/parser.cpp
@@ -416,9 +416,8 @@ wcstring parser_t::stack_trace() const {
 /// NULL otherwise. This is tested by moving down the block-scope-stack, checking every block if it
 /// is of type FUNCTION_CALL. If the caller doesn't specify a starting position in the stack we
 /// begin with the current block.
-const wchar_t *parser_t::is_function(size_t idx) const {
-    for (size_t block_idx = idx; block_idx < block_list.size(); block_idx++) {
-        const block_t &b = block_list[block_idx];
+const wchar_t *parser_t::is_function() const {
+    for (const auto &b : block_list) {
         if (b.is_function_call()) {
             return b.function_name.c_str();
         } else if (b.type() == block_type_t::source) {
diff --git a/src/parser.h b/src/parser.h
index f7822e751..19fa21110 100644
--- a/src/parser.h
+++ b/src/parser.h
@@ -285,7 +285,7 @@ class parser_t : public std::enable_shared_from_this<parser_t> {
     /// Returns the name of the currently evaluated function if we are currently evaluating a
     /// function, null otherwise. This is tested by moving down the block-scope-stack, checking
     /// every block if it is of type FUNCTION_CALL.
-    const wchar_t *is_function(size_t idx = 0) const;
+    const wchar_t *is_function() const;
 
     /// Create a parser.
     parser_t();