diff -up 0.6.0/GNUmakefile.orig 0.6.0/GNUmakefile

--- 0.6.0/GNUmakefile.orig	2021-05-20 15:27:51.181168867 +0200

+++ 0.6.0/GNUmakefile	2021-05-20 15:28:02.489222506 +0200

@@ -12,9 +12,9 @@ MAKEFLAGS += --no-builtin-rules

 WARNINGS = -Wall -Wextra -Wpedantic -Wformat=2 -Wstrict-aliasing=3 -Wstrict-overflow=5 -Wstack-usage=12500 \

 	-Wfloat-equal -Wcast-align -Wpointer-arith -Wchar-subscripts -Warray-bounds=2 -Wno-unknown-warning-option

-override CFLAGS ?= -g -O2 $(WARNINGS) $(EXTRA_WARNINGS)

+override CFLAGS += -g -O2 $(WARNINGS) $(EXTRA_WARNINGS)

 override CFLAGS += -std=c99

-override CPPFLAGS ?= -D_FORTIFY_SOURCE=2

+override CPPFLAGS += -D_FORTIFY_SOURCE=2

 override CPPFLAGS += -DBM_VERSION=\"$(VERSION)\" -DBM_PLUGIN_VERSION=\"$(VERSION)-$(GIT_SHA1)\" -DINSTALL_LIBDIR=\"$(PREFIX)$(libdir)\"

 override CPPFLAGS += -D_DEFAULT_SOURCE -Ilib