diff --git a/src/complete.cpp b/src/complete.cpp
index c81de5f1e..bb17b0310 100644
--- a/src/complete.cpp
+++ b/src/complete.cpp
@@ -671,8 +671,11 @@ void completer_t::complete_cmd(const wcstring &str_cmd, bool use_function, bool
     if (use_implicit_cd) {
         // We don't really care if this succeeds or fails. If it succeeds this->completions will be
         // updated with choices for the user.
-        (void)expand_string(str_cmd, &this->completions,
-                            EXPAND_FOR_COMPLETIONS | DIRECTORIES_ONLY | this->expand_flags(), NULL);
+        expand_error_t ignore =
+            expand_string(str_cmd, &this->completions,
+                          EXPAND_FOR_COMPLETIONS | DIRECTORIES_ONLY | this->expand_flags(),
+                          NULL);
+        USE(ignore);
     }
 
     if (str_cmd.find(L'/') == wcstring::npos && str_cmd.at(0) != L'~') {
diff --git a/src/input.cpp b/src/input.cpp
index cfd409cdc..9e9989b84 100644
--- a/src/input.cpp
+++ b/src/input.cpp
@@ -493,7 +493,7 @@ static void input_mapping_execute(const input_mapping_t &m, bool allow_commands)
 
 /// Try reading the specified function mapping.
 static bool input_mapping_is_match(const input_mapping_t &m) {
-    wint_t c = 0;
+    wchar_t c = 0;
     int j;
 
     debug(2, L"trying to match mapping %ls", escape(m.seq.c_str(), ESCAPE_ALL).c_str());
diff --git a/src/pager.cpp b/src/pager.cpp
index c4b9c7e2a..70373b0af 100644
--- a/src/pager.cpp
+++ b/src/pager.cpp
@@ -183,7 +183,6 @@ void pager_t::completion_print(size_t cols, const size_t *width_by_column, size_
                                size_t row_stop, const wcstring &prefix, const comp_info_list_t &lst,
                                page_rendering_t *rendering) const {
     // Teach the rendering about the rows it printed.
-    assert(row_start >= 0);
     assert(row_stop >= row_start);
     rendering->row_start = row_start;
     rendering->row_end = row_stop;
@@ -456,7 +455,7 @@ bool pager_t::completion_try_print(size_t cols, const wcstring &prefix, const co
         size_t last_starting_row = row_count - term_height;
         start_row = mini(suggested_start_row, last_starting_row);
         stop_row = start_row + term_height;
-        assert(start_row >= 0 && start_row <= last_starting_row);
+        assert(start_row <= last_starting_row);
     }
 
     assert(stop_row >= start_row);
diff --git a/src/parse_execution.cpp b/src/parse_execution.cpp
index ea7ab6e40..5f6c9a6ba 100644
--- a/src/parse_execution.cpp
+++ b/src/parse_execution.cpp
@@ -103,7 +103,6 @@ node_offset_t parse_execution_context_t::get_offset(const parse_node_t &node) co
     const parse_node_t *addr = &node;
     const parse_node_t *base = &this->tree.at(0);
     assert(addr >= base);
-    assert(addr - base < SOURCE_OFFSET_INVALID);
     node_offset_t offset = static_cast<node_offset_t>(addr - base);
     assert(offset < this->tree.size());
     assert(&tree.at(offset) == &node);
diff --git a/src/parse_tree.cpp b/src/parse_tree.cpp
index 121ffc513..f3bbdbf43 100644
--- a/src/parse_tree.cpp
+++ b/src/parse_tree.cpp
@@ -1326,10 +1326,12 @@ bool parse_node_tree_t::argument_list_is_root(const parse_node_t &node) const {
 enum parse_statement_decoration_t parse_node_tree_t::decoration_for_plain_statement(
     const parse_node_t &node) const {
     assert(node.type == symbol_plain_statement);
+    parse_statement_decoration_t decoration = parse_statement_decoration_none;
     const parse_node_t *decorated_statement = this->get_parent(node, symbol_decorated_statement);
-    parse_node_tag_t tag =
-        decorated_statement ? decorated_statement->tag : parse_statement_decoration_none;
-    return static_cast<parse_statement_decoration_t>(tag);
+    if (decorated_statement) {
+        decoration = static_cast<parse_statement_decoration_t>(decorated_statement->tag);
+    }
+    return decoration;
 }
 
 bool parse_node_tree_t::command_for_plain_statement(const parse_node_t &node, const wcstring &src,
diff --git a/src/parse_tree.h b/src/parse_tree.h
index 7b994fbd6..dc932a782 100644
--- a/src/parse_tree.h
+++ b/src/parse_tree.h
@@ -20,7 +20,7 @@ typedef uint32_t node_offset_t;
 
 typedef uint32_t source_offset_t;
 
-#define SOURCE_OFFSET_INVALID (static_cast<source_offset_t>(-1))
+constexpr source_offset_t SOURCE_OFFSET_INVALID = static_cast<source_offset_t>(-1);
 
 /// A struct representing the token type that we use internally.
 struct parse_token_t {
diff --git a/src/parse_util.cpp b/src/parse_util.cpp
index 361214fcd..f0a6177c8 100644
--- a/src/parse_util.cpp
+++ b/src/parse_util.cpp
@@ -347,8 +347,6 @@ void parse_util_token_extent(const wchar_t *buff, size_t cursor_pos, const wchar
 
     CHECK(buff, );
 
-    assert(cursor_pos >= 0);
-
     const wchar_t *cmdsubst_begin, *cmdsubst_end;
     parse_util_cmdsubst_extent(buff, cursor_pos, &cmdsubst_begin, &cmdsubst_end);
 
@@ -840,7 +838,7 @@ void parse_util_expand_variable_error(const wcstring &token, size_t global_token
             // report a bracket error. Otherwise just complain about the ${.
             bool looks_like_variable = false;
             size_t closing_bracket =
-                token.find(char_after_dollar == L'{' ? L'}' : BRACKET_END, dollar_pos + 2);
+                token.find(char_after_dollar == L'{' ? L'}' : wchar_t(BRACKET_END), dollar_pos + 2);
             wcstring var_name;
             if (closing_bracket != wcstring::npos) {
                 size_t var_start = dollar_pos + 2, var_end = closing_bracket;