diff --git a/GNUmakefile b/GNUmakefile
index 27eee508..25796761 100644
--- a/GNUmakefile
+++ b/GNUmakefile
@@ -19,9 +19,10 @@ mandir  ?= $(prefix)/man
 suffix  ?=
 
 CC      ?= gcc
+CFLAGS_EXTRA ?=
 LD      ?= ld
 MDBX_OPTIONS ?= -DNDEBUG=1
-CFLAGS  ?= -O2 -g -Wall -Werror -Wextra -Wpedantic -ffunction-sections -fPIC -fvisibility=hidden -std=gnu11 -pthread -Wno-error=attributes
+CFLAGS  ?= -O2 -g -Wall -Werror -Wextra -Wpedantic -ffunction-sections -fPIC -fvisibility=hidden -std=gnu11 -pthread -Wno-error=attributes $(CFLAGS_EXTRA)
 # -Wno-tautological-compare
 
 # HINT: Try append '--no-as-needed,-lrt' for ability to built with modern glibc, but then run with the old.