diff --git a/src/db.c b/src/db.c
index 4a1c7f8..0384ea7 100644
--- a/src/db.c
+++ b/src/db.c
@@ -15,7 +15,7 @@ struct node {
 _pure_ static inline size_t
 db_size(const uint8_t *a)
 {
-    return (a[0] ?: str_len((char *)a + 1)) + 1;
+    return (a[0] ?: str_len((char *)a + 1, 4096)) + 1;
 }
 
 _pure_ static inline size_t
diff --git a/src/str.h b/src/str.h
index b1197b0..302933d 100644
--- a/src/str.h
+++ b/src/str.h
@@ -24,12 +24,12 @@ str_cmp(const char *restrict sa, const char *restrict sb)
 }
 
 _pure_ static inline size_t
-str_len(const char *restrict str)
+str_len(const char *restrict str, size_t len)
 {
     if (!str)
         return 0;
 
-    return strlen(str);
+    return strnlen(str, len);
 }
 
 static inline size_t
@@ -42,7 +42,7 @@ str_cat(char *dst, const char **src, size_t count, size_t dst_len)
     size_t p = 0;
 
     for (size_t i = 0; i < count; i++) {
-        size_t n = str_len(src[i]);
+        size_t n = str_len(src[i], dst_len - len);
 
         if (!n)
             continue;