diff --git a/Makefile-AVR b/Makefile-AVR
index 4e0a0b9..7edaa6c 100644
--- a/Makefile-AVR
+++ b/Makefile-AVR
@@ -113,6 +113,7 @@ TARGET = $(PROGRAM).hex
 # to keep this working and can take a shortcut:
 SOURCES = $(wildcard *.c)
 
+CFLAGS  = $(EXTRA_CFLAGS)
 CFLAGS += -DF_CPU=$(F_CPU)
 CFLAGS += -DMCU_STR=\"$(MCU)\"
 CFLAGS += -mmcu=$(MCU)
diff --git a/Makefile-SIM b/Makefile-SIM
index baf4cd2..60fff20 100644
--- a/Makefile-SIM
+++ b/Makefile-SIM
@@ -44,6 +44,7 @@ SOURCES = $(wildcard *.c)
 SIM_SOURCES = $(subst $(SIM_PATH)/,,$(wildcard $(SIM_PATH)/*.c))
 SOURCES := $(filter-out $(subst _sim.c,.c,$(SIM_SOURCES)),$(SOURCES)) $(SIM_SOURCES)
 
+CFLAGS  = $(EXTRA_CFLAGS)
 CFLAGS += -g -Wall -Wstrict-prototypes -Wno-format -Os $(DEFS) -std=gnu99
 CFLAGS += -funsigned-char -funsigned-bitfields -fshort-enums -I.. -I.
 CFLAGS += -DSIMULATOR -Wno-format -Wno-format-security
diff --git a/Makefile-common b/Makefile-common
index 84c2d5b..0ce7532 100644
--- a/Makefile-common
+++ b/Makefile-common
@@ -107,3 +107,29 @@ $(BUILDDIR)/%.bin: $(BUILDDIR)/%.elf
 $(BUILDDIR)/%.sym: $(BUILDDIR)/%.elf
 	@echo "  SYM       $@"
 	@$(OBJDUMP) -t $< | perl -ne 'BEGIN { printf "  ADDR  NAME                  SIZE\n"; } /([0-9a-f]+)\s+(\w+)\s+O\s+\.(bss|data)\s+([0-9a-f]+)\s+(\w+)/ && printf "0x%04x  %-20s +%d\n", eval("0x$$1") & 0xFFFF, $$5, eval("0x$$4")' | sort -k1 > $@
+
+
+# Helpful tools.
+
+.PHONY: regressiontests
+
+# Try to catch regressions. Put here whatever test can help to detect these
+# and can be automated enough to allow to run them with a simple
+# "make regressiontests".
+regressiontests:
+	# Generic Gen7 configuration.
+	$(MAKE) -f Makefile-AVR USER_CONFIG=testcases/config.regtest-gen7.h \
+	  MCU=atmega644 F_CPU=20000000UL EXTRA_CFLAGS=-Werror all
+	# Generic RAMPS configuration.
+	$(MAKE) -f Makefile-AVR USER_CONFIG=testcases/config.regtest-ramps.h \
+	  MCU=atmega2560 F_CPU=16000000UL EXTRA_CFLAGS=-Werror all
+	# Generic Teensy2 configuration, which uses USB_SERIAL.
+	$(MAKE) -f Makefile-AVR USER_CONFIG=testcases/config.regtest-teensy2.h \
+	  MCU=atmega32u4 F_CPU=16000000UL EXTRA_CFLAGS=-Werror all
+	# Don't forget the hostside simulator.
+	$(MAKE) -f Makefile-SIM all
+	@# Nonstandard builds go into a subdirectory of build/, see definition of
+	@# $(BUILDDIR) above. Let's clean that up on success.
+	rm -rf $(BUILDDIR)/testcases/ $(BUILDDIR)/sim/
+	@echo
+	@echo "All regression tests ran successfully, you're fine to commit now."
diff --git a/testcases/config.regtest-gen7.h b/testcases/config.regtest-gen7.h
new file mode 100644
index 0000000..43936b2
--- /dev/null
+++ b/testcases/config.regtest-gen7.h
@@ -0,0 +1,6 @@
+
+// Configuration for controller board.
+#include "../config/board.gen7-v1.4.h"
+
+// Configuration for printer board.
+#include "../config/printer.wolfstrap.h"
diff --git a/testcases/config.regtest-ramps.h b/testcases/config.regtest-ramps.h
new file mode 100644
index 0000000..9ea4f6f
--- /dev/null
+++ b/testcases/config.regtest-ramps.h
@@ -0,0 +1,6 @@
+
+// Configuration for controller board.
+#include "../config/board.ramps-v1.3.h"
+
+// Configuration for printer board.
+#include "../config/printer.mendel.h"
diff --git a/testcases/config.regtest-teensy2.h b/testcases/config.regtest-teensy2.h
new file mode 100644
index 0000000..52844e0
--- /dev/null
+++ b/testcases/config.regtest-teensy2.h
@@ -0,0 +1,6 @@
+
+// Configuration for controller board.
+#include "../config/board.teensy-v2.0.h"
+
+// Configuration for printer board.
+#include "../config/printer.mendel.h"