diff --git a/tests/Makefile.am b/tests/Makefile.am
new file mode 100644
index 0000000..29f629e
--- /dev/null
+++ b/tests/Makefile.am
@@ -0,0 +1,14 @@
+check_PROGRAMS = captdefilter test-hiscoa
+
+hiscoa_decompress = \
+	hiscoa-decompress.c \
+	hiscoa-decompress.h
+
+captdefilter_SOURCES = captdefilter.c \
+	$(hiscoa_decompress)
+
+test_hiscoa_SOURCES = test-hiscoa.c \
+	../src/hiscoa-compress.c \
+	$(hiscoa_decompress)
+
+AM_CFLAGS = -std=c99 -Wall -Wextra -pedantic -I../src
diff --git a/tests/captdefilter.c b/tests/captdefilter.c
index a6b0894..5b815da 100644
--- a/tests/captdefilter.c
+++ b/tests/captdefilter.c
@@ -1,6 +1,4 @@
-
-#include "../src/word.h"
-#include "scoa-decompress.h"
+#include "word.h"
 #include "hiscoa-decompress.h"
 
 #include <stdbool.h>
@@ -19,7 +17,6 @@ static struct page page;
 
 static bool hi_mode = false;
 static unsigned line_size;
-static uint8_t *buffer_line;
 static struct hiscoa_params hiscoa_params;
 
 static uint8_t *page_reserve(size_t size)
@@ -64,6 +61,8 @@ static void dump(const uint8_t *buf, size_t size)
 
 static void decode_hiscoa_params(const uint8_t *buf, size_t size)
 {
+	(void) size;
+
 	hiscoa_params.origin_3 = (int8_t)buf[0];
 	hiscoa_params.origin_5 = (int8_t)buf[1];
 	/* buf[2] - ??? */
@@ -98,16 +97,22 @@ static void decode_hiscoa_band_data(const uint8_t *buf, size_t size, unsigned li
 
 static void decode_hiscoa_band(const uint8_t *buf, size_t size)
 {
-	unsigned lines = WORD(buf[0], buf[1]);
-	decode_hiscoa_band_data(buf + 2, size - 2, lines);
+	unsigned lines = WORD(buf[2], buf[3]);
+	decode_hiscoa_band_data(buf + 4, size - 4, lines);
 }
 
-static void decode_hiscoa_band3(const uint8_t *buf, size_t size)
+static void decode_hiscoa_band2(const uint8_t *buf, size_t size)
 {
-	unsigned lines = WORD(buf[0], buf[1]);
+	unsigned lines = WORD(buf[2], buf[3]);
 	decode_hiscoa_band_data(buf + 6, size - 6, lines);
 }
 
+static void decode_hiscoa_band3(const uint8_t *buf, size_t size)
+{
+	unsigned lines = WORD(buf[2], buf[3]);
+	decode_hiscoa_band_data(buf + 8, size - 8, lines);
+}
+
 static void dispatch(uint16_t cmd, const uint8_t *buf, size_t size)
 {
 	switch (cmd) {
@@ -126,9 +131,6 @@ static void dispatch(uint16_t cmd, const uint8_t *buf, size_t size)
 		dump(buf, size);
 		line_size = WORD(buf[26], buf[27]);
 		fprintf(stderr, "  decoded: L=%u bytes, %u pixels\n", line_size, line_size * 8);
-		buffer_line=calloc(line_size, sizeof(uint8_t));
-		if (! buffer_line)
-			abort();
 		break;
 	case 0xD0A4:
 		fprintf(stderr, "  -(Hi-SCoA parameters)-\n");
@@ -142,6 +144,7 @@ static void dispatch(uint16_t cmd, const uint8_t *buf, size_t size)
 		break;
 	case 0xC0A0:
 		if (! hi_mode) {
+			fprintf(stderr, "  -(SCoA data)-\n");
 			dump(buf, 16);
 		} else {
 			fprintf(stderr, "  -(Hi-SCoA data from printer debug)-\n");
@@ -151,12 +154,12 @@ static void dispatch(uint16_t cmd, const uint8_t *buf, size_t size)
 		break;
 	case 0x8000:
 		fprintf(stderr, "  -(Hi-SCoA data)-\n");
-		dump(buf + 2, 4);
-		decode_hiscoa_band(buf, size);
+		dump(buf, 4);
+		decode_hiscoa_band2(buf, size);
 		break;
 	case 0x8200:
 		fprintf(stderr, "  -(Hi-SCoA data)-\n");
-		dump(buf + 6, 4);
+		dump(buf, 4);
 		decode_hiscoa_band3(buf, size);
 		break;
 	case 0xC0A4:
@@ -171,7 +174,6 @@ static void dispatch(uint16_t cmd, const uint8_t *buf, size_t size)
 
 int main(int argc, char **argv)
 {
-	unsigned iband;
 	static uint8_t buf[1<<20];
 
 	FILE *input = stdin;
@@ -226,25 +228,12 @@ int main(int argc, char **argv)
 			fprintf(stderr, "! unable to read %li bytes\n", len - pos);
 			break;
 		}
-		switch (cmd) {
-		case 0x8000:
-			dispatch(cmd, buf + pos, len - pos);
-			break;
-		case 0x8200:
-			dispatch(cmd, buf + pos - 6, len - pos + 6);
-			break;
-		default:
-			dispatch(cmd, buf + pos, len - pos);
-			break;
-		}
+		dispatch(cmd, buf + pos, len - pos);
 	}
 
 	if (page.size)
 		page_output();
 
-	if (buffer_line)
-		free(buffer_line);
-
 	if (argc > 1)
 		fclose(input);
 	return 0;
diff --git a/tests/captdefilter.c.orig b/tests/captdefilter.c.orig
deleted file mode 100644
index 4e6e8da..0000000
--- a/tests/captdefilter.c.orig
+++ /dev/null
@@ -1,227 +0,0 @@
-
-#include "word.h"
-#include "hiscoa-decompress.h"
-
-#include <stdbool.h>
-#include <stdio.h>
-#include <stdlib.h>
-#include <stdint.h>
-#include <string.h>
-
-struct page {
-	size_t reserve;
-	size_t size;
-	uint8_t *data;
-};
-
-static struct page page;
-
-static bool hi_mode = false;
-static unsigned line_size;
-static struct hiscoa_params hiscoa_params;
-
-static uint8_t *page_reserve(size_t size)
-{
-	size_t reserve = page.reserve;
-	while (page.size + size > reserve)
-		reserve *= 2;
-	if (reserve != page.reserve) {
-		page.reserve = reserve;
-		page.data = realloc(page.data, page.reserve);
-		if (! page.data)
-			abort();
-	}
-	return page.data + page.size;
-}
-
-static void page_add(const uint8_t *buf, size_t size)
-{
-	memcpy(page_reserve(size), buf, size);
-	page.size += size;
-}
-
-static void page_output(void)
-{
-	unsigned w = line_size * 8;
-	unsigned h = page.size / line_size;
-	printf("P4\n#\n%u %u\n", w, h);
-	fwrite(page.data, line_size, h, stdout);
-	fprintf(stderr, "output page %ux%u px\n", w, h);
-	page.size = 0;
-}
-
-static void dump(const uint8_t *buf, size_t size)
-{
-	size_t i;
-	for (i = 1; i <= size; ++i) {
-		fprintf(stderr, " %02x", buf[i - 1]);
-		if (i % 16 == 0 || i == size)
-			fprintf(stderr, "\n");
-	}
-}
-
-static void decode_hiscoa_params(const uint8_t *buf, size_t size)
-{
-	hiscoa_params.origin_3 = (int8_t)buf[0];
-	hiscoa_params.origin_5 = (int8_t)buf[1];
-	/* buf[2] - ??? */
-	/* buf[3] - ??? */
-	hiscoa_params.origin_0 = (int8_t) buf[4]; /* ??? */
-	hiscoa_params.origin_2 = (int8_t) buf[5];
-	hiscoa_params.origin_4 = (int16_t) WORD(buf[6], buf[7]);
-}
-
-static void decode_hiscoa_band_data(const uint8_t *buf, size_t size, unsigned lines)
-{
-	const uint8_t *src;
-	size_t srcsize;
-	uint8_t *dest;
-	size_t destsize = 0;
-	unsigned type;
-	src = buf;
-	srcsize = size;
-	hiscoa_decompress_band((const void **)&src, &srcsize,
-			NULL, &destsize, line_size, &hiscoa_params);
-	dest = page_reserve(destsize);
-	src = buf;
-	srcsize = size;
-	type = hiscoa_decompress_band((const void **)&src, &srcsize,
-			dest, &destsize, line_size, &hiscoa_params);
-	page.size += destsize;
-	fprintf(stderr, "  eob = %u, lines = %u, expected bytes = %u\n",
-		type, lines, lines * line_size);
-	fprintf(stderr, "  unconsumed size = %u, decompressed size = %u\n",
-		(unsigned) srcsize, (unsigned) destsize);
-}
-
-static void decode_hiscoa_band(const uint8_t *buf, size_t size)
-{
-	unsigned lines = WORD(buf[2], buf[3]);
-	decode_hiscoa_band_data(buf + 4, size - 4, lines);
-}
-static void decode_hiscoa_band2(const uint8_t *buf, size_t size)
-{
-	unsigned lines = WORD_(buf[2], buf[3]);
-	decode_hiscoa_band_data(buf + 8, size - 8, lines);
-}
-static void dispatch(uint16_t cmd, const uint8_t *buf, size_t size)
-{
-	switch (cmd) {
-	case 0xD0A9:
-		fprintf(stderr, "  --(multi-command)--\n");
-		while (size) {
-			uint16_t cc = WORD(buf[0], buf[1]);
-			unsigned cs = WORD(buf[2], buf[3]);
-			dispatch(cc, buf + 4, cs - 4);
-			buf += cs;
-			size -= cs;
-		}
-		break;
-	case 0xD0A0:
-		fprintf(stderr, "  -(compression parameters)-\n");
-		dump(buf, size);
-		line_size = WORD(buf[26], buf[27]);
-		fprintf(stderr, "  decoded: L=%u bytes, %u pixels\n", line_size, line_size * 8);
-		break;
-	case 0xD0A4:
-		fprintf(stderr, "  -(Hi-SCoA parameters)-\n");
-		dump(buf, size);
-		decode_hiscoa_params(buf, size);
-		hi_mode = true;
-		fprintf(stderr, "  decoded: [0]=%i+L [2]=%i+L [4]=%i [3]=%i [5]=%i\n",
-			hiscoa_params.origin_0, hiscoa_params.origin_2,
-			hiscoa_params.origin_4,
-			hiscoa_params.origin_3, hiscoa_params.origin_5);
-		break;
-	case 0xC0A0:
-		if (! hi_mode) {
-			fprintf(stderr, "  -(SCoA data)-\n");
-			dump(buf, 16);
-		} else {
-			fprintf(stderr, "  -(Hi-SCoA data from printer debug)-\n");
-			dump(buf, 4);
-			decode_hiscoa_band_data(buf, size, 70);
-		}
-		break;
-	case 0x8000:
-		fprintf(stderr, "  -(Hi-SCoA data)-\n");
-		dump(buf, 4);
-		decode_hiscoa_band(buf, size);
-		break;
-	case 0x8200:
-		fprintf(stderr, "  -(Hi-SCoA data 0x8200)-\n");
-		dump(buf, 4);
-		decode_hiscoa_band2(buf, size);
-		break;
-	case 0xC0A4:
-		fprintf(stderr, "  --end--\n");
-		page_output();
-		break;
-	default:
-		dump(buf, size);
-		break;
-	}
-}
-
-int main(int argc, char **argv)
-{
-	unsigned iband;
-	static uint8_t buf[1<<20];
-
-	FILE *input = stdin;
-
-	if (argc > 1) {
-		input = fopen(argv[1], "r");
-		if (! input)
-			abort();
-	}
-
-	page.reserve = 1024;
-	page.size = 0;
-	page.data = malloc(page.reserve);
-	if (! page.data)
-		abort();
-
-	while (1) {
-		int s;
-		uint16_t cmd;
-		uint32_t len;
-		size_t pos;
-		s = fread(buf, 1, 4, input);
-		if (s == 0)
-			break;
-		if (s != 4) {
-			fprintf(stderr, "! unable to read header\n");
-			break;
-		}
-		pos = 4;
-		cmd = WORD(buf[0], buf[1]);
-		switch (cmd) {
-		case 0x8200:
-			fread(buf + pos, 1, 4, input);
-			pos += 4;
-			len = WORD(buf[6], buf[7]);
-			len <<= 16;
-			len += WORD(buf[4], buf[5]);
-			pos=0;
-			fseek(input, -8, SEEK_CUR);
-			break;
-		default:
-			len = WORD(buf[2], buf[3]);
-			break;
-		}
-		fprintf(stderr, "CMD %04X len=%u\n", cmd, len);
-		if (fread(buf + pos, 1, len - pos, input) != len - pos) {
-			fprintf(stderr, "! unable to read %u bytes\n", len - pos);
-			break;
-		}
-		dispatch(cmd, buf + pos, len - pos);
-	}
-
-	if (page.size)
-		page_output();
-
-	if (argc > 1)
-		fclose(input);
-	return 0;
-}