diff --git a/mk/flags.mk b/mk/flags.mk
index 1326271f7..23e40abdf 100644
--- a/mk/flags.mk
+++ b/mk/flags.mk
@@ -35,6 +35,13 @@ YYFLAGS  += -Wno-other # --debug --verbose
 LLFLAGS  +=
 LDFLAGS += $(MARCH)
 
+
+# do not cause the "free nonheap object"-waning to cause an error
+# code generated by bison may cause gcc11 to errornously detect such a condition. 
+ifeq "$(CXX)" "g++"
+CXXFLAGS += -Wno-free-nonheap-object
+endif
+
 # Add boost library search path.
 # This is the defualt installation location by home brew.
 ifeq "$(is_darwin)" "1"