diff --git a/examples/pthreads/pthreads.tm b/examples/pthreads/pthreads.tm
index 13d94e4..b4671d4 100644
--- a/examples/pthreads/pthreads.tm
+++ b/examples/pthreads/pthreads.tm
@@ -58,14 +58,14 @@ struct IntQueue(_queue:@[Int], _mutex:@pthread_mutex_t, _cond:@pthread_cond_t):
         return IntQueue(@initial, pthread_mutex_t.new(), pthread_cond_t.new())
 
     func give(q:IntQueue, n:Int):
-        begin: q._mutex:lock()
-        end: q._mutex:unlock()
+        do_begin: q._mutex:lock()
+        do_end: q._mutex:unlock()
         do: q._queue:insert(n)
         q._cond:signal()
 
     func take(q:IntQueue -> Int):
-        begin: q._mutex:lock()
-        end: q._mutex:unlock()
+        do_begin: q._mutex:lock()
+        do_end: q._mutex:unlock()
         do:
             repeat:
                 if n := q._queue:pop(1):
@@ -79,8 +79,8 @@ func main():
 
     say_mutex := pthread_mutex_t.new()
     announce := func(speaker:Text, text:Text):
-        begin: say_mutex:lock()
-        end: say_mutex:unlock()
+        do_begin: say_mutex:lock()
+        do_end: say_mutex:unlock()
         do: say("$\033[2m[$speaker]$\033[m $text")
 
     worker := pthread_t.new(func():
diff --git a/parse.c b/parse.c
index 5110e98..93876cf 100644
--- a/parse.c
+++ b/parse.c
@@ -53,7 +53,7 @@ int op_tightness[] = {
 static const char *keywords[] = {
     "yes", "xor", "while", "when", "use", "unless", "struct", "stop", "skip", "return",
     "or", "not", "none", "no", "mutexed", "mod1", "mod", "pass", "lang", "inline", "in", "if", "holding",
-    "func", "for", "extern", "enum", "end", "else", "do", "deserialize", "defer", "begin", "and",
+    "func", "for", "extern", "enum", "do_end", "else", "do", "deserialize", "defer", "do_begin", "and",
     "_min_", "_max_", NULL,
 };
 
@@ -1172,16 +1172,16 @@ PARSER(parse_for) {
 }
 
 PARSER(parse_do) {
-    // [begin: [<indent>] block] [end: [<indent>] block] do: [<indent>] body
+    // [do_begin: [<indent>] block] [do_end: [<indent>] block] do: [<indent>] body
     const char *start = pos;
     int64_t starting_indent = get_indent(ctx, pos);
     ast_t *begin = NULL, *end = NULL;
-    if (match_word(&pos, "begin"))
+    if (match_word(&pos, "do_begin"))
         begin = optional(ctx, &pos, parse_block);
 
     const char *tmp = pos;
     whitespace(&tmp);
-    if (get_indent(ctx, tmp) == starting_indent && match_word(&tmp, "end")) {
+    if (get_indent(ctx, tmp) == starting_indent && match_word(&tmp, "do_end")) {
         pos = tmp;
         end = optional(ctx, &pos, parse_block);
     }