diff --git a/test/readme.txt b/test/readme.txt
index 49ae363cc..dd87ea9df 100644
--- a/test/readme.txt
+++ b/test/readme.txt
@@ -12,6 +12,13 @@ compiler is working as expected (when the tests behave as described):
 /val  - The bulk of tests are contained here, individual tests should exit with
         an exit code of EXIT_SUCCESS when they pass, or EXIT_FAILURE on error.
 
+/standard - like the tests in /val, the tests must exit with EXIT_SUCCESS on
+        success. Unlike the tests in /val these are not compiled for every
+        combination of optimizer options, but instead always with -Osir and then
+        for each supported C-standard (C89, C99, CC65). The goal is to use these
+        to check for regressions in standard conformance of the compiler and the
+        library.
+
 /ref  - These tests produce output that must be compared with reference output.
 
 /err  - contains tests that MUST NOT compile
diff --git a/test/standard/Makefile b/test/standard/Makefile
new file mode 100644
index 000000000..054623b79
--- /dev/null
+++ b/test/standard/Makefile
@@ -0,0 +1,63 @@
+# Makefile for the regression tests that return an error code on failure
+
+ifneq ($(shell echo),)
+  CMD_EXE = 1
+endif
+
+ifdef CMD_EXE
+  S = $(subst /,\,/)
+  NULLDEV = nul:
+  MKDIR = mkdir $(subst /,\,$1)
+  RMDIR = -rmdir /s /q $(subst /,\,$1)
+else
+  S = /
+  NULLDEV = /dev/null
+  MKDIR = mkdir -p $1
+  RMDIR = $(RM) -r $1
+endif
+
+ifdef QUIET
+  .SILENT:
+  NULLOUT = >$(NULLDEV)
+  NULLERR = 2>$(NULLDEV)
+endif
+
+SIM65FLAGS = -x 5000000000 -c
+
+CC65 := $(if $(wildcard ../../bin/cc65*),..$S..$Sbin$Scc65,cc65)
+CA65 := $(if $(wildcard ../../bin/ca65*),..$S..$Sbin$Sca65,ca65)
+LD65 := $(if $(wildcard ../../bin/ld65*),..$S..$Sbin$Sld65,ld65)
+SIM65 := $(if $(wildcard ../../bin/sim65*),..$S..$Sbin$Ssim65,sim65)
+
+WORKDIR = ../../testwrk/standard
+
+OPTIONS = c89 c99 cc65
+
+.PHONY: all clean
+
+SOURCES := $(wildcard *.c)
+TESTS  = $(foreach option,$(OPTIONS),$(SOURCES:%.c=$(WORKDIR)/%.$(option).6502.prg))
+#TESTS += $(foreach option,$(OPTIONS),$(SOURCES:%.c=$(WORKDIR)/%.$(option).65c02.prg))
+
+all: $(TESTS)
+
+$(WORKDIR):
+	$(call MKDIR,$(WORKDIR))
+
+define PRG_template
+
+$(WORKDIR)/%.$1.$2.prg: %.c | $(WORKDIR)
+	$(if $(QUIET),echo standard/$$*.$1.$2.prg)
+	$(CC65) -t sim$2 $$(CC65FLAGS) -Osir --add-source --standard $1 -o $$(@:.prg=.s) $$< $(NULLERR)
+	$(CA65) -t sim$2 -o $$(@:.prg=.o) $$(@:.prg=.s) $(NULLERR)
+	$(LD65) -t sim$2 -o $$@ $$(@:.prg=.o) sim$2.lib $(NULLERR)
+	$(SIM65) $(SIM65FLAGS) $$@ > $(WORKDIR)/$$@.out
+
+endef # PRG_template
+
+$(foreach option,$(OPTIONS),$(eval $(call PRG_template,$(option),6502)))
+
+#$(foreach option,$(OPTIONS),$(eval $(call PRG_template,$(option),65c02)))
+
+clean:
+	@$(call RMDIR,$(WORKDIR))
diff --git a/test/standard/bug1670.c b/test/standard/bug1670.c
new file mode 100644
index 000000000..038b40067
--- /dev/null
+++ b/test/standard/bug1670.c
@@ -0,0 +1,33 @@
+
+/* #1670 - Standard headers contain non standard identifiers in C89/C99 mode */
+
+#include <stdlib.h>
+#include <stdio.h>
+#include <time.h>
+
+#if __CC65_STD__ != __CC65_STD_CC65__
+/* implement our own clock_gettime, using a different signature than the POSIX one */
+const char* clock_gettime(void)
+{
+    static char buf[32];
+    struct tm *my_tm;
+#if 0
+    /* FIXME: this will not work in the simulator */
+    time_t t = time(NULL);
+#else
+    time_t t = 0x12345678;
+#endif
+    my_tm = localtime(&t);
+    printf("%2d:%2d:%2d\n", my_tm->tm_hour, my_tm->tm_min, my_tm->tm_sec);
+    strftime(buf, sizeof(buf), "<%H:%M:%S>", my_tm);
+    return buf;
+}
+#endif
+
+int main(void)
+{
+#if __CC65_STD__ != __CC65_STD_CC65__
+    printf("The time is %s\n", clock_gettime());
+#endif
+    return EXIT_SUCCESS;
+}