diff --git a/GNUmakefile b/GNUmakefile
index b0773609..99d28ae2 100644
--- a/GNUmakefile
+++ b/GNUmakefile
@@ -83,7 +83,7 @@ MAN_SRCDIR := man1/
 
 config.h: mdbx.c $(lastword $(MAKEFILE_LIST))
 	(echo '#define MDBX_BUILD_TIMESTAMP "$(shell date +%Y-%m-%dT%H:%M:%S%z)"' \
-	&& echo '#define MDBX_BUILD_FLAGS "$(CFLAGS) $(LDFLAGS) $(LIBS)"' \
+	&& echo '#define MDBX_BUILD_FLAGS "$(CXXSTD) $(CFLAGS) $(LDFLAGS) $(LIBS)"' \
 	&& echo '#define MDBX_BUILD_COMPILER "$(shell (LC_ALL=C $(CC) --version || echo 'Please use GCC or CLANG compatible compiler') | head -1)"' \
 	&& echo '#define MDBX_BUILD_TARGET "$(shell set -o pipefail; (LC_ALL=C $(CC) -v 2>&1 | grep -i '^Target:' | cut -d ' ' -f 2- || (LC_ALL=C $(CC) --version | grep -qi e2k && echo E2K) || echo 'Please use GCC or CLANG compatible compiler') | head -1)"' \
 	) > $@
@@ -236,7 +236,7 @@ src/version.c: src/version.c.in $(lastword $(MAKEFILE_LIST)) $(git_DIR)/HEAD $(g
 
 src/config.h: src/version.c $(lastword $(MAKEFILE_LIST))
 	(echo '#define MDBX_BUILD_TIMESTAMP "$(shell date +%Y-%m-%dT%H:%M:%S%z)"' \
-	&& echo '#define MDBX_BUILD_FLAGS "$(CFLAGS) $(LDFLAGS) $(LIBS)"' \
+	&& echo '#define MDBX_BUILD_FLAGS "$(CXXSTD) $(CFLAGS) $(LDFLAGS) $(LIBS)"' \
 	&& echo '#define MDBX_BUILD_COMPILER "$(shell (LC_ALL=C $(CC) --version || echo 'Please use GCC or CLANG compatible compiler') | head -1)"' \
 	&& echo '#define MDBX_BUILD_TARGET "$(shell set -o pipefail; (LC_ALL=C $(CC) -v 2>&1 | grep -i '^Target:' | cut -d ' ' -f 2- || (LC_ALL=C $(CC) --version | grep -qi e2k && echo E2K) || echo 'Please use GCC or CLANG compatible compiler') | head -1)"' \
 	&& echo '#define MDBX_BUILD_SOURCERY $(MDBX_BUILD_SOURCERY)' \