diff --git a/Makefile b/Makefile
index c985497e..36229b94 100644
--- a/Makefile
+++ b/Makefile
@@ -141,13 +141,13 @@ endif
 ifeq ($(WARN),1)
 ALL_CFLAGS += -Wstrict-prototypes -Wshadow -Wpointer-arith -Wcast-qual \
             -Wcast-align -Wwrite-strings -Wnested-externs -Winline -W \
-            -Wmissing-prototypes
+            -Wmissing-prototypes -Wundef
 endif
 
 ALL_CPPFLAGS += $(CPPFLAGS)
 ALL_CFLAGS += $(CFLAGS)
 
-PROGCPPFLAGS := -DETCDIR="\"$(ETCDIR)\"" $(ALL_CPPFLAGS) -Wundef
+PROGCPPFLAGS := -DETCDIR="\"$(ETCDIR)\"" $(ALL_CPPFLAGS)
 PROGCFLAGS := $(ALL_CFLAGS)
 ARCPPFLAGS := $(ALL_CPPFLAGS)
 ARCFLAGS := $(ALL_CFLAGS)
diff --git a/lib/Module.mk b/lib/Module.mk
index abfd3d69..9cfdadf3 100644
--- a/lib/Module.mk
+++ b/lib/Module.mk
@@ -85,10 +85,18 @@ $(MODULE_DIR)/conf-parse.h: $(MODULE_DIR)/conf-parse.c
 INCLUDEFILES += $(LIBCSOURCES:.c=.ld) $(LIBCSOURCES:.c=.ad)
 
 # Special warning prevention for flex-generated files
+FLEXNOWARN:=-Wno-shadow -Wno-undef -Wno-unused -Wno-missing-prototypes
 $(MODULE_DIR)/conf-lex.ao: $(MODULE_DIR)/conf-lex.c
-	$(CC) $(ARCPPFLAGS) $(ARCFLAGS) -Wno-unused -Wno-missing-prototypes -c $< -o $@
+	$(CC) $(ARCPPFLAGS) $(ARCFLAGS) $(FLEXNOWARN) -c $< -o $@
 $(MODULE_DIR)/conf-lex.lo: $(MODULE_DIR)/conf-lex.c
-	$(CC) $(LIBCPPFLAGS) $(LIBCFLAGS) -Wno-unused -Wno-missing-prototypes -c $< -o $@
+	$(CC) $(LIBCPPFLAGS) $(LIBCFLAGS) $(FLEXNOWARN) -c $< -o $@
+
+# Special warning prevention for bison-generated files
+YACCNOWARN:=-Wno-undef
+$(MODULE_DIR)/conf-parse.ao: $(MODULE_DIR)/conf-parse.c
+	$(CC) $(ARCPPFLAGS) $(ARCFLAGS) $(YACCNOWARN) -c $< -o $@
+$(MODULE_DIR)/conf-parse.lo: $(MODULE_DIR)/conf-parse.c
+	$(CC) $(LIBCPPFLAGS) $(LIBCFLAGS) $(YACCNOWARN) -c $< -o $@
 
 REMOVELIBST := $(patsubst $(MODULE_DIR)/%,$(DESTDIR)$(LIBDIR)/%,$(LIB_DIR)/$(LIBSTLIBNAME))
 REMOVELIBSH := $(patsubst $(MODULE_DIR)/%,$(DESTDIR)$(LIBDIR)/%,$(LIB_DIR)/$(LIBSHLIBNAME))