diff --git a/zet.dpi.c b/zet.dpi.c
index af16b35..8e3449e 100644
--- a/zet.dpi.c
+++ b/zet.dpi.c
@@ -7,6 +7,7 @@
 #include <dirent.h>
 #include <fcntl.h>
 #include <limits.h>
+#include <regex.h>
 #include <stdarg.h>
 #include <stdbool.h>
 #include <stdio.h>
@@ -66,7 +67,8 @@ struct http_request {
 struct zet_search {
 	DIR *dir;
 	const char *id;
-	char *query;
+	regex_t regex;
+	bool has_regex;
 };
 
 struct zet_mtime {
@@ -335,7 +337,7 @@ static int zet_links_to(const char *id_from, const char *id_to) {
 	return rc;
 }
 
-static int zet_matches_query(const char *id, const char *query) {
+static int zet_matches_regex(const char *id, regex_t *regex) {
 	char path_buf[_POSIX_PATH_MAX];
 	ssize_t sz = snprintf(path_buf, sizeof(path_buf), "%s/%s", zet_dir, id);
 	if (sz < 0 || (size_t)sz >= sizeof(path_buf)) return -1;
@@ -344,17 +346,38 @@ static int zet_matches_query(const char *id, const char *query) {
 	if (note_fd < 0) return -1;
 
 	char *text = read_full(note_fd);
-	bool found = strcasestr(text, query) != NULL;
+	bool found = regexec(regex, text, 0, NULL, 0) == 0;
 	free(text);
 	return found ? 1 : 0;
 }
 
+static int zet_search_init_query(struct zet_search *zs, const char *query) {
+	int rc = regcomp(&zs->regex, query, REG_NOSUB | REG_EXTENDED | REG_ICASE);
+	if (rc != 0) {
+		char errbuf[LINE_MAX];
+		size_t sz = regerror(rc, &zs->regex, errbuf, sizeof(errbuf));
+		if (sz > sizeof(errbuf)-1) {
+			errbuf[sizeof(errbuf)-2] = '.';
+			errbuf[sizeof(errbuf)-3] = '.';
+			errbuf[sizeof(errbuf)-4] = '.';
+		}
+		warnx("regex: %s", errbuf);
+		return -1;
+	}
+	return 0;
+}
+
 static int zet_search_start(struct zet_search *zs, const char *id, char *query) {
 	zs->dir = opendir(zet_dir);
 	if (zs->dir == NULL) return -1;
 	zs->id = id;
-	zs->query = query;
-	return 0;
+	if (query != NULL) {
+		zs->has_regex = true;
+		return zet_search_init_query(zs, query);
+	} else {
+		zs->has_regex = false;
+		return 0;
+	}
 }
 
 static int zet_search_next(struct zet_search *zs, const char **idp) {
@@ -362,7 +385,6 @@ static int zet_search_next(struct zet_search *zs, const char **idp) {
 	struct dirent *ent;
 	const char *id;
 	const char *dest_id = zs->id;
-	const char *query = zs->query;
 	while (1) {
 		errno = 0;
 		ent = readdir(zs->dir);
@@ -379,8 +401,8 @@ static int zet_search_next(struct zet_search *zs, const char **idp) {
 			if (rc < 0) return -1;
 			if (rc != 1) continue;
 		}
-		if (query != NULL) {
-			rc = zet_matches_query(id, query);
+		if (zs->has_regex) {
+			rc = zet_matches_regex(id, &zs->regex);
 			if (rc < 0) return -1;
 			if (rc != 1) continue;
 		}
@@ -391,6 +413,7 @@ static int zet_search_next(struct zet_search *zs, const char **idp) {
 }
 
 static int zet_search_close(struct zet_search *sz) {
+	regfree(&sz->regex);
 	return closedir(sz->dir);
 }