diff --git a/.github/workflows/snek.yml b/.github/workflows/snek.yml
index 69b6f02..067c9f7 100644
--- a/.github/workflows/snek.yml
+++ b/.github/workflows/snek.yml
@@ -26,7 +26,7 @@ jobs:
           docker run --rm \
             --mount type=bind,source=`pwd`/artifacts,destination=/artifacts \
             snek \
-            make DESTDIR=/artifacts PREFIX=/opt/snek check install
+            make DESTDIR=/artifacts PREFIX=/opt/snek SNEK_RISCV_TEST=1 check install
 
       - name: 'Upload results'
         uses: actions/upload-artifact@v2
diff --git a/Makefile b/Makefile
index 7274d6d..e47c9b2 100644
--- a/Makefile
+++ b/Makefile
@@ -36,35 +36,9 @@ FORCE:
 
 check: all
 	+cd test && make $@
-	+black --check --exclude 'fail-syntax-.*\.py' .
+	+black --check --exclude 'fail-syntax-.*\.py|.*/hosts/.*.py' .
 
-SHAREFILES = \
-	snek.defs \
-	$(SNEK_SRC) \
-	$(SNEK_EXT_SRC) \
-	$(SNEK_RAW_INC) \
-	$(SNEK_EXT_INC) \
-	$(SNEK_BUILTINS) \
-	$(SNEK_EXT_BUILTINS) \
-	$(SNEK_ROOT)/snek-gram.ll \
-	$(SNEK_ROOT)/snek-builtin.py
-
-IMAGEFILES = \
-	snek.svg
-
-DOCFILES = \
-	$(IMAGEFILES)
-
-PKGFILES = \
-	snek.pc
-
-install: $(SHAREFILES) $(PKGFILES) $(DOCFILES)
-	install -d $(DESTDIR)$(SHAREDIR)
-	for i in $(SHAREFILES); do install --mode=644 "$$i" $(DESTDIR)$(SHAREDIR) || exit 1; done
-	install -d $(DESTDIR)$(PKGCONFIG)
-	for i in $(PKGFILES); do install --mode=644 "$$i" $(DESTDIR)$(PKGCONFIG) || exit 1; done
-	install -d $(DESTDIR)$(DOCDIR)
-	for i in $(DOCFILES); do install --mode=644 "$$i" $(DESTDIR)$(DOCDIR) || exit 1; done
+install:
 	+for dir in $(SUBDIRS); do (cd $$dir && make PREFIX=$(PREFIX) DESTDIR=$(DESTDIR) $@) || exit 1; done
 	+for snek in $(SNEKS); do (cd `dirname $$snek` && make PREFIX=$(PREFIX) DESTDIR=$(DESTDIR) $@) || exit 1; done
 
@@ -76,9 +50,6 @@ otheros: $(SNEKS)
 	+cd doc && make
 	+for otheros in $(SNEK_OTHEROS_DIR); do (cd "$$otheros" && make); done
 
-snek.pc: snek.pc.in
-	$(SNEK_SED) $^ > $@
-
 snek-mu.py:
 	find . -name '*.builtin' -print0 | xargs -0 python3 ./snek-builtin.py --mu -o $@
 
@@ -86,6 +57,5 @@ docker:
 	docker build -t phsilva/snek .
 
 clean:
-	rm -f snek.pc
 	+for dir in $(SUBDIRS); do (cd $$dir && make PREFIX=$(PREFIX) DESTDIR=$(DESTDIR) $@); done
 	+for snek in $(SNEKS); do (cd `dirname $$snek` && make PREFIX=$(PREFIX) DESTDIR=$(DESTDIR) $@); done
diff --git a/chips/avr/snek-avr.defs b/chips/avr/snek-avr.defs
index d099784..5c9d7a1 100644
--- a/chips/avr/snek-avr.defs
+++ b/chips/avr/snek-avr.defs
@@ -56,7 +56,8 @@ CFLAGS = $(AVR_CFLAGS) $(SNEK_CFLAGS)
 
 LDSCRIPT=$(SNEK_AVR)/snek-avr51.x
 
-LDFLAGS=-Wl,-uvfprintf -lprintf_flt -lm \
+LDFLAGS=$(SNEK_LDFLAGS) \
+	-Wl,-uvfprintf -lprintf_flt -lm \
 	-Wl,--defsym -Wl,__TEXT_REGION_LENGTH__=0x8000 \
 	-Wl,--defsym -Wl,__DATA_REGION_LENGTH__=0x880 \
 	-Wl,--defsym -Wl,__EEPROM_REGION_LENGTH__=0x400 \
diff --git a/chips/qemu/snek-qemu.defs b/chips/qemu/snek-qemu.defs
index 87e3125..84d51fb 100644
--- a/chips/qemu/snek-qemu.defs
+++ b/chips/qemu/snek-qemu.defs
@@ -40,7 +40,7 @@ CFLAGS=$(ARCH_CFLAGS) --oslib=semihost \
 	-std=gnu99 $(OPT) -g \
 	-I. -I$(SNEK_QEMU) -I$(SNEK_ROOT) $(PICOLIBC_CFLAGS) $(SNEK_CFLAGS)
 
-LDFLAGS=$(CFLAGS) -n
+LDFLAGS=$(SNEK_LDFLAGS) $(CFLAGS) -n
 
 LIBS=-lm
 
diff --git a/chips/samd21/snek-samd21.defs b/chips/samd21/snek-samd21.defs
index c51ba38..3f34eea 100644
--- a/chips/samd21/snek-samd21.defs
+++ b/chips/samd21/snek-samd21.defs
@@ -81,7 +81,7 @@ CFLAGS = $(SAMD21_CFLAGS) $(SNEK_CFLAGS)
 
 LDSCRIPT=$(SNEK_SAMD21)/snek-samd21.ld
 
-LDFLAGS=$(CFLAGS) -Wl,-T$(SNEK_SAMD21)/registers.ld -T$(LDSCRIPT)  -n
+LDFLAGS=$(SNEK_LDFLAGS) $(CFLAGS) -Wl,-T$(SNEK_SAMD21)/registers.ld -T$(LDSCRIPT)  -n
 
 LIBS=-lm
 
diff --git a/hosts/macosx/Makefile b/hosts/macosx/Makefile
index b16a151..1cec439 100644
--- a/hosts/macosx/Makefile
+++ b/hosts/macosx/Makefile
@@ -64,7 +64,7 @@ snek-bits: $(SNEK_FILES) macosx
 	cp -p $(SNEK_SCRIPTS) macosx/snek.app/Contents/MacOS/
 endif
 
-$(MACOSX_DIST): $(MACOSX_FILES) macosx
+$(MACOSX_DIST): $(MACOSX_FILES) macosx snek-bits
 	rm -f $@
 	cp -a $(MACOSX_DOCS) macosx
 	cp -a $(MACOSX_INSTALL) macosx
diff --git a/hosts/macosx/build-mac b/hosts/macosx/build-mac
index 980f305..189181b 100755
--- a/hosts/macosx/build-mac
+++ b/hosts/macosx/build-mac
@@ -28,12 +28,13 @@ esac
 
 build="$1"
 builddir=`echo $build | sed 's/^[^:]*://'`
+buildhost=`echo $build | sed 's/:.*$//'`
 echo builddir "$builddir"
 
 target="$2"
 
 rsync -Ravz --delete `git ls-files` "$build"
 
-ssh imac-remote "cd '$builddir'/ports/posix && make"
+ssh $buildhost "cd '$builddir'/ports/posix && make"
 
 rsync -avz "$build"/ports/posix/snek "$curdir"/"$target"
diff --git a/ports/duemilanove/Makefile b/ports/duemilanove/Makefile
index 2f0f0e1..98cd30b 100644
--- a/ports/duemilanove/Makefile
+++ b/ports/duemilanove/Makefile
@@ -44,7 +44,8 @@ CC=avr-gcc
 OPT=-Os -frename-registers -funsigned-char -fno-jump-tables -mcall-prologues
 
 CFLAGS=$(OPT) -DF_CPU=16000000UL -mmcu=atmega328p -I. -I$(SNEK_LOCAL_VPATH) -g $(SNEK_CFLAGS) -Waddr-space-convert
-LDFLAGS=-Wl,-uvfprintf -lprintf_flt -lm \
+LDFLAGS=$(SNEK_LDFLAGS) \
+	-Wl,-uvfprintf -lprintf_flt -lm \
 	-Wl,--defsym -Wl,__TEXT_REGION_LENGTH__=0x7e00 \
 	-Wl,--defsym -Wl,__DATA_REGION_LENGTH__=0x7a0 \
 	-Wl,--defsym -Wl,__EEPROM_REGION_LENGTH__=0x400 \
diff --git a/ports/duemilanove/snek-duemilanove-install.1 b/ports/duemilanove/snek-duemilanove-install.1
index c998ce1..84fcbcb 100644
--- a/ports/duemilanove/snek-duemilanove-install.1
+++ b/ports/duemilanove/snek-duemilanove-install.1
@@ -23,8 +23,8 @@ Duemilanove board.
 .SH OPTIONS
 .TP
 \-isp <ISP model>
-Specifies the programmer to use, common options are 'optiboot', 
-'usbtiny', and 'avrisp2'. The default is 'optiboot'.
+Specifies the programmer to use, common options are optiboot, 
+usbtiny, and avrisp2. The default is optiboot.
 .TP
 \-hex <snek.hex>
 Specifies the hex file to load to the board. The default is the
diff --git a/ports/esp32/.gitignore b/ports/esp32/.gitignore
index d054d84..f04d3d5 100644
--- a/ports/esp32/.gitignore
+++ b/ports/esp32/.gitignore
@@ -1,3 +1,4 @@
 build
 sdkconfig
 sdkconfig.old
+*.bin
diff --git a/ports/esp32/Makefile b/ports/esp32/Makefile
index 47db7fe..28d98e9 100644
--- a/ports/esp32/Makefile
+++ b/ports/esp32/Makefile
@@ -12,7 +12,8 @@
 # General Public License for more details.
 #
 
-include ../../snek.defs
+SNEK_ROOT = ../..
+include ../../snek-install.defs
 
 ESP32_IDF ?= ./esp32-idf
 
@@ -37,3 +38,7 @@ load:
 
 connect:
 	minicom -D /dev/ttyUSB1 -b 115200
+
+install: $(TARGET)
+	install -d $(DESTDIR)$(SHAREDIR)
+	install -m 0644 $(TARGET) $(DESTDIR)$(SHAREDIR)
diff --git a/ports/hifive1revb/Makefile b/ports/hifive1revb/Makefile
index 5338f77..31ba670 100644
--- a/ports/hifive1revb/Makefile
+++ b/ports/hifive1revb/Makefile
@@ -63,7 +63,7 @@ HIFIVE1REVB_CFLAGS=-march=rv32imac -mabi=ilp32 \
 
 CFLAGS = $(HIFIVE1REVB_CFLAGS) $(SNEK_CFLAGS) $(AO_CFLAGS)
 
-LDFLAGS=$(CFLAGS) -n -Wl,--gc-sections
+LDFLAGS=$(SNEK_LDFLAGS) $(CFLAGS) -n
 
 LIBS=-lm
 
diff --git a/ports/mega/Makefile b/ports/mega/Makefile
index fb39d81..7b21278 100644
--- a/ports/mega/Makefile
+++ b/ports/mega/Makefile
@@ -48,7 +48,8 @@ HEX=$(BASE).hex
 MAP=$(BASE).map
 CC=avr-gcc
 CFLAGS=-Os -DF_CPU=16000000UL -mmcu=atmega2560 -I. -I$(SNEK_LOCAL_VPATH) -g -fno-jump-tables $(SNEK_CFLAGS) -mcall-prologues -Waddr-space-convert
-LDFLAGS=-Wl,-uvfprintf -lprintf_flt -lm \
+LDFLAGS=$(SNEK_LDFLAGS) \
+	-Wl,-uvfprintf -lprintf_flt -lm \
 	-Wl,--defsym -Wl,__TEXT_REGION_LENGTH__=0x3e000 \
 	-Wl,--defsym -Wl,__DATA_REGION_LENGTH__=0x1e00 \
 	-Wl,--defsym -Wl,__EEPROM_REGION_LENGTH__=0x1000 \
diff --git a/ports/posix/snek-main.c b/ports/posix/snek-main.c
index e6465c3..b778397 100644
--- a/ports/posix/snek-main.c
+++ b/ports/posix/snek-main.c
@@ -21,7 +21,7 @@ FILE	*snek_posix_input;
 
 static const struct option options[] = {
 	{ .name = "version", .has_arg = 0, .val = 'v' },
-	{ .name = "file", .has_arg = 1, .val = 'f' },
+	{ .name = "interactive", .has_arg = 0, .val = 'i' },
 	{ .name = "help", .has_arg = 0, .val = '?' },
 	{ .name = NULL, .has_arg = 0, .val = 0 },
 };
@@ -29,7 +29,7 @@ static const struct option options[] = {
 static void
 usage (char *program, int val)
 {
-	fprintf(stderr, "usage: %s [--version] [--help] [--file <file.py>] <program.py>\n", program);
+	fprintf(stderr, "usage: %s [--version] [--help] [--interactive] <program.py>\n", program);
 	exit(val);
 }
 
@@ -71,16 +71,17 @@ int
 main (int argc, char **argv)
 {
 	int c;
-	char *file = NULL;
+	bool do_interactive = true;
+	bool interactive_flag = false;
 
-	while ((c = getopt_long(argc, argv, "v?f:", options, NULL)) != -1) {
+	while ((c = getopt_long(argc, argv, "v?i", options, NULL)) != -1) {
 		switch (c) {
 		case 'v':
 			printf("%s version %s\n", argv[0], SNEK_VERSION);
 			exit(0);
 			break;
-		case 'f':
-			file = optarg;
+		case 'i':
+			interactive_flag = true;
 			break;
 		case '?':
 			usage(argv[0], 0);
@@ -93,15 +94,7 @@ main (int argc, char **argv)
 
 	snek_init();
 
-	if (file) {
-		snek_file = file;
-		snek_posix_input = fopen(snek_file, "r");
-		if (!snek_posix_input) {
-			perror(snek_file);
-			exit(1);
-		}
-		snek_parse();
-	}
+	bool ret = true;
 
 	if (argv[optind]) {
 		snek_file = argv[optind];
@@ -110,18 +103,21 @@ main (int argc, char **argv)
 			perror(snek_file);
 			exit(1);
 		}
-	} else {
+		if (snek_parse() != snek_parse_success)
+			ret = false;
+		fclose(snek_posix_input);
+		do_interactive = interactive_flag;
+	}
+
+	if (do_interactive) {
+		printf("Welcome to Snek version %s\n", SNEK_VERSION);
 		snek_file = "<stdin>";
 		snek_posix_input = stdin;
 		snek_interactive = true;
-		printf("Welcome to Snek version %s\n", SNEK_VERSION);
+		if (snek_parse() != snek_parse_success)
+			ret = false;
+		printf("\n");
 	}
 
-	bool ret = snek_parse() == snek_parse_success;
-
-	if (snek_posix_input == stdin)
-		printf("\n");
-	else
-		fclose(snek_posix_input);
 	return ret ? 0 : 1;
 }
diff --git a/ports/posix/snek.1 b/ports/posix/snek.1
index 94237a2..5632856 100644
--- a/ports/posix/snek.1
+++ b/ports/posix/snek.1
@@ -15,14 +15,29 @@
 .SH NAME
 snek \- Snek Programming Language
 .SH SYNOPSIS
-.B "snek" {program.py}
+.B "snek" [--version|-v] [--help|-?] [--interactive|-i] [program.py]
 .SH DESCRIPTION
 .I snek
 is a small Python-derivative suitable for embedded computers. This
 host version is largely designed to help test the Snek system and
 applications on larger machines
+.SH COMMAND LINE OPTIONS
+.TP
+\--version or \-v
+Reports the version number to stdout and then exits.
+.TP
+\--help or \-?
+Prints usage information to stdout and then exits.
+.TP
+\--interactive or \-i
+When a program is specified on the command line, enter interactive
+mode after executing that program.
 .SH USAGE
-If you specify a program file on the command line, snek will load and
-execute this instead of reading from the command line.
+When a program is specified on the command line, snek runs it. Then,
+if the --interactive flag is passed, it enters interactive
+mode. Otherwise, it exits.
+.P
+When no program is specified on the command line, snek enters
+interactive mode.
 .SH AUTHOR
 Keith Packard
diff --git a/snek-list.c b/snek-list.c
index 52b7e74..4d6d0a4 100644
--- a/snek-list.c
+++ b/snek-list.c
@@ -280,7 +280,7 @@ snek_list_imm(snek_offset_t size, snek_list_type_t type)
 			s -= 2;
 			snek_poly_t key = snek_stack_pick(s+1);
 			snek_poly_t value = snek_stack_pick(s);
-			snek_poly_t *ref = _snek_list_ref(list, key, false, true);
+			snek_poly_t *ref = _snek_list_ref(list, key, true, true);
 			if (ref)
 				*ref = value;
 		}
diff --git a/snek-poly.c b/snek-poly.c
index c557f6f..7b60c78 100644
--- a/snek-poly.c
+++ b/snek-poly.c
@@ -84,11 +84,13 @@ snek_poly_cmp(snek_poly_t a, snek_poly_t b, bool is)
 	int8_t tdiff = atype - btype;
 	if (tdiff)
 		return tdiff;
+	int sdiff;
 	switch (atype) {
 	case snek_float:
 		return (b.f < a.f) - (a.f < b.f);
 	case snek_string:
-		return strcmp(snek_poly_to_string(a), snek_poly_to_string(b));
+		sdiff = strcmp(snek_poly_to_string(a), snek_poly_to_string(b));
+		return (sdiff > 0) - (sdiff < 0);
 	case snek_list:
 		if (!is)
 			return snek_list_cmp(snek_poly_to_list(a), snek_poly_to_list(b));
diff --git a/snek.defs b/snek.defs
index 699e229..e51df64 100644
--- a/snek.defs
+++ b/snek.defs
@@ -7,11 +7,13 @@ vpath %.ll $(SNEK_LOCAL_VPATH):$(SNEK_ROOT)
 vpath %.py $(SNEK_LOCAL_VPATH):$(SNEK_ROOT)
 vpath %.builtin $(SNEK_LOCAL_VPATH):$(SNEK_ROOT)
 
-SNEK_VERSION = 1.4
-SNEK_DATE = 2020-05-13
+SNEK_VERSION = 1.4.1
+SNEK_DATE = 2020-05-22
 
 SNEK_VERSION_DASH = $(shell echo $(SNEK_VERSION) | sed 's/\./-/g')
 
+SNEK_CLANG = $(shell if $(CC) --version | grep -q -i llvm; then echo yes; else echo no; fi)
+
 SNEK_PORTS = $(SNEK_ROOT)/ports
 SNEK_HOSTS = $(SNEK_ROOT)/hosts
 SNEK_DOC = $(SNEK_ROOT)/doc
@@ -79,19 +81,25 @@ SNEK_MOST_WARNINGS =  \
 	-Wmissing-prototypes \
 	-Wmissing-declarations \
 	-Wnested-externs \
-	-Warray-bounds=2 \
 	-Wshadow
 
+ifeq ($(SNEK_CLANG),yes)
+SNEK_MOST_WARNINGS += -Warray-bounds
+else
+SNEK_MOST_WARNINGS += -Warray-bounds=2
+endif
+
 SNEK_WARNINGS = \
 	$(SNEK_MOST_WARNINGS) \
 	-Wimplicit-fallthrough
 
 SNEK_BASE_CFLAGS = \
-	-Wl,--gc-sections \
 	-D_DEFAULT_SOURCE \
 	-I$(SNEK_ROOT) $(SNEK_LOCAL_CFLAGS) \
 	-DSNEK_VERSION='"$(SNEK_VERSION)"'
 
+SNEK_LDFLAGS = -Wl,--gc-sections 
+
 SNEK_CFLAGS ?= $(SNEK_WARNINGS) $(SNEK_BASE_CFLAGS)
 
 SNEK_SED = sed \
diff --git a/snek.pc.in b/snek.pc.in
deleted file mode 100644
index 2f9ded8..0000000
--- a/snek.pc.in
+++ /dev/null
@@ -1,6 +0,0 @@
-sneklib=@SNEKLIB@
-
-Name: snek
-Description: Snek. A tiny python-esque language
-Version: @SNEK_VERSION@
-Cflags: -I${sneklib}
diff --git a/test/Makefile b/test/Makefile
index ea8493b..ad69a28 100644
--- a/test/Makefile
+++ b/test/Makefile
@@ -18,10 +18,14 @@ include $(SNEK_ROOT)/snek.defs
 
 PYTHON3?=python3
 SNEK_NATIVE?=$(SNEK_PORTS)/posix/snek
+ifdef SNEK_RISCV_TEST
 SNEK_RISCV?=$(SNEK_PORTS)/qemu-riscv/snek-riscv
+else
+SNEK_RISCV=
+endif
 SNEK_ARM?=$(SNEK_PORTS)/qemu-arm/snek-arm
 
-LANGS=python3 $(SNEK_NATIVE) $(SNEK_ARM)
+LANGS=python3 $(SNEK_NATIVE) $(SNEK_ARM) $(SNEK_RISCV)
 
 SUCCESS_TESTS = \
 	pass-andor.py \
@@ -72,6 +76,7 @@ FAIL_TESTS = \
 	fail-interpolate-missing.py \
 	fail-interpolate-extra.py \
 	fail-interpolate-badformat.py \
+	fail-dictionary-mutable.py \
 	$(SYNTAX_TESTS)
 
 check:
diff --git a/test/fail-dictionary-mutable.py b/test/fail-dictionary-mutable.py
new file mode 100644
index 0000000..bb3e3cf
--- /dev/null
+++ b/test/fail-dictionary-mutable.py
@@ -0,0 +1,14 @@
+#
+# Copyright © 2020 Keith Packard <keithp@keithp.com>
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful, but
+# WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+# General Public License for more details.
+#
+a = {{"hello": "world"}: "foo"}