diff --git a/src/51d.c b/src/51d.c
index 1f1a5f969..baeb2c277 100644
--- a/src/51d.c
+++ b/src/51d.c
@@ -547,6 +547,11 @@ static int init_51degrees(void)
 	if (!global_51degrees.data_file_path)
 		return 0;
 
+	if (global.nbthread > 1) {
+		Alert("51Degrees: multithreading is not supported for now.\n");
+		return (ERR_FATAL | ERR_ALERT);
+	}
+
 	if (!LIST_ISEMPTY(&global_51degrees.property_names)) {
 		i = 0;
 		list_for_each_entry(name, &global_51degrees.property_names, list)
diff --git a/src/da.c b/src/da.c
index 856ef0dad..c31855d52 100644
--- a/src/da.c
+++ b/src/da.c
@@ -121,6 +121,12 @@ static int init_deviceatlas(void)
 		size_t atlasimglen;
 		da_status_t status;
 
+		if (global.nbthread > 1) {
+			Alert("deviceatlas: multithreading is not supported for now.\n");
+			err_code |= ERR_ALERT | ERR_FATAL;
+			goto out;
+		}
+
 		jsonp = fopen(global_deviceatlas.jsonpath, "r");
 		if (jsonp == 0) {
 			Alert("deviceatlas : '%s' json file has invalid path or is not readable.\n",
diff --git a/src/wurfl.c b/src/wurfl.c
index 5bd9a0c5a..0349a50f9 100644
--- a/src/wurfl.c
+++ b/src/wurfl.c
@@ -313,6 +313,11 @@ static int ha_wurfl_init(void)
 		return ERR_WARN;
 	}
 
+	if (global.nbthread > 1) {
+		Alert("WURFL: multithreading is not supported for now.\n");
+		return (ERR_FATAL | ERR_ALERT);
+	}
+
 	if (wurfl_set_root(global_wurfl.handle, global_wurfl.data_file) != WURFL_OK) {
 		Warning("WURFL: Engine setting root file failed - %s\n", wurfl_get_error_message(global_wurfl.handle));
 		send_log(NULL, LOG_WARNING, "WURFL: Engine setting root file failed - %s\n", wurfl_get_error_message(global_wurfl.handle));