diff --git a/src/basic/strbuf.c b/src/basic/strbuf.c
index 5a416ce286..8b8281bb3b 100644
--- a/src/basic/strbuf.c
+++ b/src/basic/strbuf.c
@@ -133,9 +133,12 @@ ssize_t strbuf_add_string(struct strbuf *str, const char *s, size_t len) {
                 return -EINVAL;
 
         /* search string; start from last character to find possibly matching tails */
-        if (len == 0)
-                return 0;
+
         str->in_count++;
+        if (len == 0) {
+                str->dedup_count++;
+                return 0;
+        }
         str->in_len += len;
 
         node = str->root;
diff --git a/src/test/test-strbuf.c b/src/test/test-strbuf.c
index 891d7b1d42..e7395ff96c 100644
--- a/src/test/test-strbuf.c
+++ b/src/test/test-strbuf.c
@@ -33,7 +33,7 @@ static ssize_t add_string(struct strbuf *sb, const char *s) {
 static void test_strbuf(void) {
         struct strbuf *sb;
         _cleanup_strv_free_ char **l;
-        ssize_t a, b, c, d, e, f, g;
+        ssize_t a, b, c, d, e, f, g, h;
 
         sb = strbuf_new();
 
@@ -44,6 +44,7 @@ static void test_strbuf(void) {
         e = add_string(sb, "aldo");    /* duplicate */
         f = add_string(sb, "do");      /* duplicate */
         g = add_string(sb, "waldorf"); /* not a duplicate: matches from tail */
+        h = add_string(sb, "");
 
         /* check the content of the buffer directly */
         l = strv_parse_nulstr(sb->buf, sb->len);
@@ -53,10 +54,11 @@ static void test_strbuf(void) {
         assert_se(streq(l[2], "foo"));
         assert_se(streq(l[3], "bar"));
         assert_se(streq(l[4], "waldorf"));
+        assert_se(l[5] == NULL);
 
         assert_se(sb->nodes_count == 5); /* root + 4 non-duplicates */
-        assert_se(sb->dedup_count == 3);
-        assert_se(sb->in_count == 7);
+        assert_se(sb->dedup_count == 4);
+        assert_se(sb->in_count == 8);
 
         assert_se(sb->in_len == 29);    /* length of all strings added */
         assert_se(sb->dedup_len == 11); /* length of all strings duplicated */
@@ -70,6 +72,7 @@ static void test_strbuf(void) {
         assert_se(e == 2);
         assert_se(f == 4);
         assert_se(g == 15);
+        assert_se(h == 0);
 
         assert_se(streq(sb->buf + a, "waldo"));
         assert_se(streq(sb->buf + b, "foo"));
@@ -78,6 +81,7 @@ static void test_strbuf(void) {
         assert_se(streq(sb->buf + e, "aldo"));
         assert_se(streq(sb->buf + f, "do"));
         assert_se(streq(sb->buf + g, "waldorf"));
+        assert_se(streq(sb->buf + h, ""));
 
         strbuf_complete(sb);
         assert_se(sb->root == NULL);