diff --git a/libowlps-resultreader/libowlps-resultreader.c b/libowlps-resultreader/libowlps-resultreader.c
index 61813bb..64d8fba 100644
--- a/libowlps-resultreader/libowlps-resultreader.c
+++ b/libowlps-resultreader/libowlps-resultreader.c
@@ -110,8 +110,16 @@ owl_result* owl_fill_result(char *csv)
               " string (empty string?)!\n") ;
       goto error ;
     }
-  result->mobile_mac_addr =
-    strndup(csv_field, OWL_ETHER_ADDR_STRLEN) ;
+  if (strnlen(csv_field, OWL_ETHER_ADDR_STRLEN)
+      != OWL_ETHER_ADDR_STRLEN - 1)
+    {
+      csv_field[OWL_ETHER_ADDR_STRLEN-1] = '\0' ;
+      fprintf(stderr,
+              "The string \"%s\" is not a valid MAC address!\n",
+              csv_field) ;
+      goto error ;
+    }
+  strncpy(result->mobile_mac_addr, csv_field, OWL_ETHER_ADDR_STRLEN) ;
 
   /* Request type */
   if (! owl_read_long_field(&csv, CSV_DELIMITER, &longfield))
@@ -528,9 +536,9 @@ void owl_fprint_algorithm_result(FILE *stream,
 
 
 /**
- * Frees the memory allocated for an `owl_result`. The `results` and
- * `mobile_mac_addr` fields of `result` *must* be defined, either to
- * `NULL` or to a valid memory block allocated with `malloc()`.
+ * Frees the memory allocated for an `owl_result`. The `results` field
+ * of `result` *must* be defined, either to `NULL` or to a valid memory
+ * block allocated with `malloc()`.
  * Note that `result` will not be set to `NULL`.
  */
 void owl_free_result(owl_result *const result)
@@ -543,7 +551,6 @@ void owl_free_result(owl_result *const result)
       result->results = algo->next ;
       owl_free_algorithm_result(algo) ;
     }
-  free(result->mobile_mac_addr) ;
   free(result) ;
 }
 
diff --git a/libowlps-resultreader/owlps-resultreader.h b/libowlps-resultreader/owlps-resultreader.h
index 05edca1..601cb38 100644
--- a/libowlps-resultreader/owlps-resultreader.h
+++ b/libowlps-resultreader/owlps-resultreader.h
@@ -96,7 +96,7 @@ typedef struct _owl_algorithm_result owl_algorithm_result ;
  */
 struct _owl_result
 {
-  char *mobile_mac_addr ; ///< Mobile's MAC address
+  char mobile_mac_addr[OWL_ETHER_ADDR_STRLEN] ; ///< Mobile's MAC address
   uint8_t request_type ; ///< Type of the request
   /// Local time on the mobile when sending the request
   owl_timestamp mobile_timestamp ;