diff --git a/make/defs-cpp.mk b/make/defs-cpp.mk
index 72276919..b2f6f08c 100644
--- a/make/defs-cpp.mk
+++ b/make/defs-cpp.mk
@@ -127,6 +127,9 @@ ifeq ($(COMPILER_SUITE),gcc)
   RANLIB                    ?= $(TC_BIN_PREFIX)ranlib
   AR                        ?= $(TC_BIN_PREFIX)ar
   PKG_CONFIG_EXE            ?= $(TC_BIN_PREFIX)pkg-config
+  CPP_FILT                  ?= $(TC_BIN_PREFIX)c++filt
+  OBJCOPY                   ?= $(TC_BIN_PREFIX)objcopy
+  OBJDUMP                   ?= $(TC_BIN_PREFIX)objdump
 
   # compiler and linker
   # gcc
@@ -423,10 +426,13 @@ ifeq ($(USE_COMPILER_OPTIMIZATION_OPTS),true)
 else
   NO_OPT_FLAGS               = \
     -O0 -g -fno-inline -fno-omit-frame-pointer \
-    -fno-builtin -fno-optimize-sibling-calls \
+    -fno-optimize-sibling-calls \
     $(GCC_NO_OPT_FLAGS)
     # -fconserve-stack
 
+  # breaks constexpr
+  #NO_OPT_FLAGS += -fno-builtin 
+
   _NO_OPT_FLAGS              = \
     -O0 \
     -fno-implicit-inline-templates \
@@ -516,7 +522,7 @@ INSTALLATION_FILE_TYPES     += LIB
 #INSTALL_PIDIR               = $(INSTALL_LIBDIR)
 #INSTALLED_PI                = $(addprefix $(INSTALL_PIDIR)/,$(PLUGIN))
 
-BUILD_LIBDIR                 = $(TOPDIR)/lib
+BUILD_LIBDIR                ?= $(TOPDIR)/lib
 
 LOCAL_LIBS                  += $(CONTRIB_LIBS) $(PLUGIN)
 ifeq ($(TARGET),mingw)