diff --git a/iowatcher/blkparse.c b/iowatcher/blkparse.c
index 43eb269..bf58b45 100644
--- a/iowatcher/blkparse.c
+++ b/iowatcher/blkparse.c
@@ -707,81 +707,123 @@
 }
 
 static char footer[] = ".blktrace.0";
-static int footer_len = sizeof(footer);
+static int footer_len = sizeof(footer) - 1;
 
-static void match_trace(char *name, char **traces)
+static int match_trace(char *name, int *len)
 {
 	int match_len;
-	char *match;
 	int footer_start;
 
 	match_len = strlen(name);
 	if (match_len <= footer_len)
-		return;
+		return 0;
 
 	footer_start = match_len - footer_len;
-	if (strcmp(name + footer_start + 1, footer) != 0)
-		return;
+	if (strcmp(name + footer_start, footer) != 0)
+		return 0;
 
-	match = strdup(name);
-	if (!match)
-		goto enomem;
-
-	match[footer_start + 1] = '\0';
-	snprintf(line, line_len, "%s -i '%s'", *traces ? *traces : "", match);
-	free(match);
-
-	match = strdup(line);
-	if (!match)
-		goto enomem;
-
-	free(*traces);
-	*traces = match;
-	return;
-
-enomem:
-	perror("memory allocation failed");
-	exit(1);
-	return;
+	if (len)
+		*len = match_len;
+	return 1;
 }
 
-static char *combine_blktrace_devs(char *dir_name)
-{
-	DIR *dir;
-	char *traces = NULL;
-	struct dirent *d;
-	int len;
-	int ret;
+struct tracelist {
+	struct tracelist *next;
+	char *name;
+};
 
-	dir = opendir(dir_name);
+static struct tracelist *traces_list(char *dir_name, int *len)
+{
+	int count = 0;
+	struct tracelist *traces = NULL;
+	DIR *dir = opendir(dir_name);
 	if (!dir)
 		return NULL;
 
 	while (1) {
-		d = readdir(dir);
+		int len;
+		struct tracelist *tl;
+		struct dirent *d = readdir(dir);
 		if (!d)
 			break;
 
-		len = strlen(d->d_name);
-		if (len > footer_len)
-			match_trace(d->d_name, &traces);
+		if (!match_trace(d->d_name, &len))
+			continue;
+
+		/* Allocate space for tracelist + filename */
+		tl = calloc(1, sizeof(struct tracelist) + (sizeof(char) * (len + 1)));
+		if (!tl)
+			return NULL;
+		tl->next = traces;
+		tl->name = (char *)(tl + 1);
+		strncpy(tl->name, d->d_name, len);
+		traces = tl;
+		count++;
 	}
 
 	closedir(dir);
 
+	if (len)
+		*len = count;
+
+	return traces;
+}
+
+static void traces_free(struct tracelist *traces)
+{
+	while (traces) {
+		struct tracelist *tl = traces;
+		traces = traces->next;
+		free(tl);
+	}
+}
+
+static char *combine_blktrace_devs(char *dir_name)
+{
+	struct tracelist *traces = NULL;
+	struct tracelist *tl;
+	char *ret = NULL;
+	char **argv = NULL;
+	char *dumpfile;
+	int argc = 0;
+	int i;
+	int err;
+
+	if (!asprintf(&dumpfile, "%s.dump", dir_name))
+		goto out;
+
+	traces = traces_list(dir_name, &argc);
 	if (!traces)
-		return NULL;
+		goto out;
 
-	snprintf(line, line_len, "blkparse -O %s -D %s -d '%s.%s'",
-		 traces, dir_name, dir_name, "dump");
+	argc *= 2; /* {"-i", trace } */
+	argc += 6; /* See below */
+	argv = calloc(argc + 1, sizeof(char *));
+	if (!argv)
+		goto out;
 
-	ret = system(line);
-	if (ret) {
-		fprintf(stderr, "blkparse failure %s\n", line);
+	i = 0;
+	argv[i++] = "blkparse";
+	argv[i++] = "-O";
+	argv[i++] = "-D";
+	argv[i++] = dir_name;
+	argv[i++] = "-d";
+	argv[i++] = dumpfile;
+	for (tl = traces; tl != NULL; tl = tl->next) {
+		argv[i++] = "-i";
+		argv[i++] = tl->name;
+	}
+
+	err = run_program2(argc, argv);
+	free(argv);
+	if (err) {
+		fprintf(stderr, "blkparse failed with exit code %d\n", err);
 		exit(1);
 	}
-	snprintf(line, line_len, "%s.%s", dir_name, "dump");
-	return strdup(line);
+	ret = dumpfile;
+out:
+	traces_free(traces);
+	return ret;
 }
 
 static char *find_trace_file(char *filename)
@@ -806,6 +848,13 @@
 			found_dir = 1;
 	}
 
+	if (found_dir) {
+		int i;
+		/* Eat up trailing '/'s */
+		for (i = strlen(filename) - 1; filename[i] == '/'; i--)
+			filename[i] = '\0';
+	}
+
 	/*
 	 * try tacking .dump onto the end and see if that already
 	 * has been generated
diff --git a/iowatcher/iowatcher.1 b/iowatcher/iowatcher.1
index 5951c7b..8a06126 100644
--- a/iowatcher/iowatcher.1
+++ b/iowatcher/iowatcher.1
@@ -27,9 +27,10 @@
 \fB-K, --keep-movie-svgs\fP
 Keep the SVG files generated for movie mode.
 .TP
-\fB-t, --trace\fP <file>
+\fB-t, --trace\fP <file|directory>
 Controls the name of the blktrace file.  iowatcher uses a dump from blkparse, so -t tries to guess the name of the corresponding per CPU blktrace data files if the dump file doesn't already exist.
 If you want more than one trace in a given graph, you can specify -t more than once.
+If a directory is specified, iowatcher will use the name of the directory as the base name of the dump file and all trace files found inside the directory will be processed.
 .TP
 \fB-l, --label\fP <label>
 Sets a label in the graph for a trace file.  The labels are added in the same order the trace files are added.
diff --git a/iowatcher/tracers.c b/iowatcher/tracers.c
index e78ecc4..8f96372 100644
--- a/iowatcher/tracers.c
+++ b/iowatcher/tracers.c
@@ -178,6 +178,26 @@
 	return 0;
 }
 
+int run_program2(int argc, char **argv)
+{
+	int i;
+	int err;
+	pid_t pid;
+
+	fprintf(stderr, "running");
+	for (i = 0; i < argc; i++)
+		fprintf(stderr, " '%s'", argv[i]);
+	fprintf(stderr, "\n");
+
+	err = posix_spawnp(&pid, argv[0], NULL, NULL, argv, environ);
+	if (err != 0) {
+		fprintf(stderr, "%s failed with exit code %d\n", argv[0], err);
+		return err;
+	}
+	waitpid(pid, NULL, 0);
+	return 0;
+}
+
 int wait_for_tracers(void)
 {
 	int status = 0;
@@ -194,9 +214,6 @@
 
 int blktrace_to_dump(char *trace_name)
 {
-	pid_t pid;
-	int err;
-	int i;
 	char *argv[] = {
 		"blkparse", "-O",
 		"-i", NULL,
@@ -208,16 +225,7 @@
 	snprintf(line, line_len, "%s.dump", trace_name);
 	argv[5] = line;
 
-	fprintf(stderr, "running blkparse");
-	for (i = 0; i < 6; i++)
-		fprintf(stderr, " %s", argv[i]);
-	fprintf(stderr, "\n");
-
-	err = posix_spawnp(&pid, "blkparse", NULL, NULL, argv, environ);
-	if (err != 0)
-		return err;
-	waitpid(pid, NULL, 0);
-	return 0;
+	return run_program2(6, argv);
 }
 
 int start_mpstat(char *trace_name)
diff --git a/iowatcher/tracers.h b/iowatcher/tracers.h
index 91e57f4..48eec45 100644
--- a/iowatcher/tracers.h
+++ b/iowatcher/tracers.h
@@ -18,6 +18,7 @@
 #ifndef __IOWATCH_TRACERS
 #define __IOWATCH_TRACERS
 int run_program(char *str);
+int run_program2(int argc, char **argv);
 int stop_blktrace(void);
 int start_blktrace(char **devices, int num_devices, char *trace_name, char *dest);
 int start_mpstat(char *trace_name);