diff --git a/tests/bonsai/rpn.mk b/tests/bonsai/rpn.mk
index 6fecab9..297295c 100755
--- a/tests/bonsai/rpn.mk
+++ b/tests/bonsai/rpn.mk
@@ -6,7 +6,7 @@
 # notice are preserved.  This file is offered as-is, without any warranty.
 
 .PHONY: rpn_tests
-rpn_tests: rpn_help rpn_add rpn_sub rpn_mul rpn_div rpn_mod rpn_flr
+rpn_tests: rpn_help rpn_add rpn_sub rpn_mul rpn_div rpn_mod rpn_flr rpn_stdin
 
 .PHONY: rpn_help
 rpn_help: $(BIN)/rpn
@@ -41,3 +41,8 @@ rpn_mod: $(BIN)/rpn
 rpn_flr: $(BIN)/rpn
 	test "$$($(BIN)/rpn 12 5 //)" -eq 2
 	test "$$($(BIN)/rpn 9 4 //)" -eq 2
+
+# done last because all operations have been tested
+.PHONY: rpn_stdin
+rpn_stdin: $(BIN)/rpn
+	test "$$(printf '1\n2\n+\n3\n-\n' | $(BIN)/rpn | tail -n1)" -eq 0