--- a/Makefile
+++ b/Makefile
@@ -10,7 +10,7 @@
 
 # features (the more the better)
 ENABLE_TCL := 1
-ENABLE_ABC := 1
+ENABLE_ABC := 0
 ENABLE_GLOB := 1
 ENABLE_PLUGINS := 1
 ENABLE_READLINE := 1
@@ -222,7 +222,7 @@
 
 ifeq ($(CONFIG),clang)
 CXX = clang++
-CXXFLAGS += -std=$(CXXSTD) $(OPT_LEVEL)
+CXXFLAGS += -std=$(CXXSTD)
 ifeq ($(ENABLE_LTO),1)
 LINKFLAGS += -fuse-ld=lld
 endif