diff --git a/Makefile b/Makefile
index f37eeac..8e6299f 100644
--- a/Makefile
+++ b/Makefile
@@ -34,4 +34,6 @@ cp:
 	cp mdbxdist/mdbx.h mdbx/
 	cp mdbxdist/mdbx.c mdbx/
 	#add 1 line to mdbx.h about build flags which we have in `mdbx.go`
+	echo "$(echo '#ifndef MDBX_BUILD_FLAGS'; cat mdbx/mdbx.h)" > mdbx/mdbx.h
 	echo "$(echo '#define MDBX_BUILD_FLAGS "-std=gnu11 -fvisibility=hidden -ffast-math"'; cat mdbx/mdbx.h)" > mdbx/mdbx.h
+	echo "$(echo '#endif'; cat mdbx/mdbx.h)" > mdbx/mdbx.h
diff --git a/mdbx/mdbx.h b/mdbx/mdbx.h
index ccb8b1c..acce125 100644
--- a/mdbx/mdbx.h
+++ b/mdbx/mdbx.h
@@ -1,3 +1,7 @@
+#ifndef MDBX_BUILD_FLAGS
+#define MDBX_BUILD_FLAGS "-std=gnu11 -fvisibility=hidden -ffast-math"
+#endif
+
 /**
 
 _libmdbx_ (aka MDBX) is an extremely fast, compact, powerful, embeddable,
@@ -38,7 +42,6 @@ credits and acknowledgments.
 #pragma once
 #ifndef LIBMDBX_H
 #define LIBMDBX_H
-#define MDBX_BUILD_FLAGS "-std=gnu11 -fvisibility=hidden -ffast-math"
 
 #if defined(__riscv) || defined(__riscv__) || defined(__RISCV) || defined(__RISCV__)
 #warning "The RISC-V architecture is intentionally insecure by design. \