diff --git a/libs/phidget21/Makefile b/libs/phidget21/Makefile
index ccfd443ed..70a2ef82d 100644
--- a/libs/phidget21/Makefile
+++ b/libs/phidget21/Makefile
@@ -21,6 +21,7 @@ include $(INCLUDE_DIR)/package.mk
 define Package/phidget21
   SECTION:=libs
   CATEGORY:=Libraries
+  DEPENDS:=+libpthread
   TITLE:=Phidget API
   URL:=http://www.phidgets.com/
 endef