diff --git a/MY-BASIC Quick Reference.pdf b/MY-BASIC Quick Reference.pdf
index 2ba635f..6b27aa6 100644
Binary files a/MY-BASIC Quick Reference.pdf and b/MY-BASIC Quick Reference.pdf differ
diff --git a/core/my_basic.c b/core/my_basic.c
index 3453fa0..ba5a472 100755
--- a/core/my_basic.c
+++ b/core/my_basic.c
@@ -12076,7 +12076,7 @@ int mb_reset(struct mb_interpreter_t** s, bool_t clrf) {
 }
 
 /* Fork a new MY-BASIC environment */
-int mb_fork(struct mb_interpreter_t** s, struct mb_interpreter_t* r, bool_t cklv) {
+int mb_fork(struct mb_interpreter_t** s, struct mb_interpreter_t* r, bool_t clfk) {
 #ifdef MB_ENABLE_FORK
 	int result = MB_FUNC_OK;
 	_running_context_t* running = 0;
@@ -12110,7 +12110,7 @@ int mb_fork(struct mb_interpreter_t** s, struct mb_interpreter_t* r, bool_t cklv
 
 	(*s)->forked_from = r;
 
-	if(cklv)
+	if(clfk)
 		_ls_pushback(r->all_forked, *s);
 
 	mb_assert(MB_FUNC_OK == result);
@@ -12119,7 +12119,7 @@ int mb_fork(struct mb_interpreter_t** s, struct mb_interpreter_t* r, bool_t cklv
 #else /* MB_ENABLE_FORK */
 	mb_unrefvar(s);
 	mb_unrefvar(r);
-	mb_unrefvar(cklv);
+	mb_unrefvar(clfk);
 
 	return MB_FUNC_ERR;
 #endif /* MB_ENABLE_FORK */
diff --git a/core/my_basic.h b/core/my_basic.h
index 38ba344..71c1de4 100755
--- a/core/my_basic.h
+++ b/core/my_basic.h
@@ -604,7 +604,7 @@ MBAPI int mb_open(struct mb_interpreter_t** s);
 MBAPI int mb_close(struct mb_interpreter_t** s);
 MBAPI int mb_reset(struct mb_interpreter_t** s, bool_t clrf/* = false*/);
 
-MBAPI int mb_fork(struct mb_interpreter_t** s, struct mb_interpreter_t* r, bool_t cklv/* = true*/);
+MBAPI int mb_fork(struct mb_interpreter_t** s, struct mb_interpreter_t* r, bool_t clfk/* = true*/);
 MBAPI int mb_join(struct mb_interpreter_t** s);
 MBAPI int mb_get_forked_from(struct mb_interpreter_t* s, struct mb_interpreter_t** src);