diff --git a/depends/packages/bdb.mk b/depends/packages/bdb.mk
--- a/depends/packages/bdb.mk
+++ b/depends/packages/bdb.mk
@@ -11,7 +11,7 @@
 $(package)_config_opts=--disable-shared --enable-cxx --disable-replication --enable-option-checking
 $(package)_config_opts_mingw32=--enable-mingw
 $(package)_config_opts_linux=--with-pic
-$(package)_cxxflags=-std=c++17
+$(package)_cxxflags+=-std=c++17
 $(package)_cppflags_mingw32=-DUNICODE -D_UNICODE
 endef
 
diff --git a/depends/packages/boost.mk b/depends/packages/boost.mk
--- a/depends/packages/boost.mk
+++ b/depends/packages/boost.mk
@@ -22,7 +22,7 @@
 $(package)_toolset_$(host_os)=gcc
 endif
 $(package)_config_libraries=atomic,date_time,test
-$(package)_cxxflags=-std=c++17 -fvisibility=hidden
+$(package)_cxxflags+=-std=c++17 -fvisibility=hidden
 $(package)_cxxflags_linux=-fPIC
 endef
 
diff --git a/depends/packages/protobuf.mk b/depends/packages/protobuf.mk
--- a/depends/packages/protobuf.mk
+++ b/depends/packages/protobuf.mk
@@ -4,7 +4,7 @@
 $(package)_file_name=$(native_$(package)_file_name)
 $(package)_sha256_hash=$(native_$(package)_sha256_hash)
 $(package)_dependencies=native_$(package)
-$(package)_cxxflags=-std=c++11
+$(package)_cxxflags+=-std=c++17
 
 define $(package)_set_vars
   $(package)_config_opts=--disable-shared --with-protoc=$(build_prefix)/bin/protoc --disable-dependency-tracking
diff --git a/depends/packages/zeromq.mk b/depends/packages/zeromq.mk
--- a/depends/packages/zeromq.mk
+++ b/depends/packages/zeromq.mk
@@ -11,7 +11,7 @@
   $(package)_config_opts += --disable-libunwind --disable-radix-tree --without-gcov --disable-dependency-tracking
   $(package)_config_opts += --disable-Werror --disable-drafts --enable-option-checking
   $(package)_config_opts_linux=--with-pic
-  $(package)_cxxflags=-std=c++17
+  $(package)_cxxflags+=-std=c++17
 endef
 
 define $(package)_preprocess_cmds