diff --git a/Makefile.rules b/Makefile.rules
index 736950e8c38fb35c93343c2e41d642715606a0f9..5402798757e5e8f16433b4a706b96147a9c8abed 100644
--- a/Makefile.rules
+++ b/Makefile.rules
@@ -11,6 +11,7 @@
 # the GNU General Public License
 #
 
+# Rules for various build phases.
 # Each command is preceded by a short comment on what to do.
 # Prefixing one or the other with @\# or @ or nothing makes the desired
 # behaviour. ECHO_PREFIX prefixes the comment, CMD_PREFIX prefixes the command.
@@ -19,52 +20,48 @@
 
 .PHONY: dist-clean
 
+# extra cflags to build dependencies. Recursively expanded.
+_CFLAGS2= -MMD -MT $@ -MF .$(subst /,_,$@).d -MP
+
 ifeq ($(NOISY_BUILD),)
-   ECHO_PREFIX=@
-   CMD_PREFIX=@
+    ECHO_PREFIX=@
+    CMD_PREFIX=@
 else
-   ECHO_PREFIX=@\# 
-   CMD_PREFIX=
+    ECHO_PREFIX=@\#
+    CMD_PREFIX=
 endif
 
 ifeq ($(findstring DONT_OPTIMIZE,$(MENUSELECT_CFLAGS)),)
-# More GSM codec optimization
-# Uncomment to enable MMXTM optimizations for x86 architecture CPU's
-# which support MMX instructions.  This should be newer pentiums,
-# ppro's, etc, as well as the AMD K6 and K7.  
-#K6OPT=-DK6OPT
-
-OPTIMIZE?=-O6
-ASTCFLAGS+=$(OPTIMIZE)
+    # More GSM codec optimization
+    # Uncomment to enable MMXTM optimizations for x86 architecture CPU's
+    # which support MMX instructions.  This should be newer pentiums,
+    # ppro's, etc, as well as the AMD K6 and K7.  
+    #K6OPT=-DK6OPT
+
+    OPTIMIZE?=-O6
+    ASTCFLAGS+=$(OPTIMIZE)
 endif
 
+# build rules for various targets
 %.o: %.c
 	$(ECHO_PREFIX) echo "   [CC] $< -> $@"
-	$(CMD_PREFIX) $(CC) -o $@ -c $< $(PTHREAD_CFLAGS) $(ASTCFLAGS) -MMD -MT $@ -MF .$(subst /,_,$@).d -MP
+	$(CMD_PREFIX) $(CC) -o $@ -c $< $(PTHREAD_CFLAGS) $(ASTCFLAGS) $(_CFLAGS2)
 
 %.o: %.i
-	$(ECHO_PREFIX) echo "   [CC] $< -> $@"
-ifeq ($(AST_DEVMODE),yes)
-	$(CMD_PREFIX) $(CC) -o $@ -c $< $(PTHREAD_CFLAGS) $(ASTCFLAGS) -MMD -MT $@ -MF .$(subst /,_,$@).d -MP
-else
-	$(CMD_PREFIX) $(CC) -o $@ -c $< $(PTHREAD_CFLAGS) $(ASTCFLAGS)
-endif
+	$(ECHO_PREFIX) echo "   [CCi] $< -> $@"
+	$(CMD_PREFIX) $(CC) -o $@ -c $< $(PTHREAD_CFLAGS) $(ASTCFLAGS) $(_CFLAGS2)
 
 %.i: %.c
-	$(ECHO_PREFIX) echo "   [CC] $< -> $@"
-ifeq ($(AST_DEVMODE),yes)
-	$(CMD_PREFIX) $(CC) -o $@ -E $< $(PTHREAD_CFLAGS) $(ASTCFLAGS) -MMD -MT $@ -MF .$(subst /,_,$@).d -MP
-else
-	$(CMD_PREFIX) $(CC) -o $@ -E $< $(PTHREAD_CFLAGS) $(ASTCFLAGS)
-endif
+	$(ECHO_PREFIX) echo "   [CPP] $< -> $@"
+	$(CMD_PREFIX) $(CC) -o $@ -E $< $(PTHREAD_CFLAGS) $(ASTCFLAGS) $(_CFLAGS2)
 
 %.o: %.s
 	$(ECHO_PREFIX) echo "   [AS] $< -> $@"
-	$(CMD_PREFIX) $(CC) -o $@ -c $< $(PTHREAD_CFLAGS) $(ASTCFLAGS) -MMD -MT $@ -MF .$(subst /,_,$@).d -MP
+	$(CMD_PREFIX) $(CC) -o $@ -c $< $(PTHREAD_CFLAGS) $(ASTCFLAGS) $(_CFLAGS2)
 
 %.oo: %.cc
 	$(ECHO_PREFIX) echo "   [CXX] $< -> $@"
-	$(CMD_PREFIX) $(CXX) -o $@ -c $< $(PTHREAD_CFLAGS) $(filter-out -Wstrict-prototypes -Wmissing-prototypes -Wmissing-declarations,$(ASTCFLAGS)) -MMD -MT $@ -MF .$(subst /,_,$@).d -MP
+	$(CMD_PREFIX) $(CXX) -o $@ -c $< $(PTHREAD_CFLAGS) $(filter-out -Wstrict-prototypes -Wmissing-prototypes -Wmissing-declarations,$(ASTCFLAGS)) $(_CFLAGS2)
 
 %.c: %.y
 	$(ECHO_PREFIX) echo "   [BISON] $< -> $@"