diff --git a/src/hlua.c b/src/hlua.c
index c2d045e..9eaa10b 100644
--- a/src/hlua.c
+++ b/src/hlua.c
@@ -754,6 +754,8 @@
 			break;
 
 		case ARGT_IPV4:
+			if (argp[idx].type != ARGT_STR)
+				WILL_LJMP(luaL_argerror(L, first + idx, "string expected"));
 			memcpy(trash.area, argp[idx].data.str.area,
 			       argp[idx].data.str.data);
 			trash.area[argp[idx].data.str.data] = 0;
@@ -772,6 +774,8 @@
 			break;
 
 		case ARGT_IPV6:
+			if (argp[idx].type != ARGT_STR)
+				WILL_LJMP(luaL_argerror(L, first + idx, "string expected"));
 			memcpy(trash.area, argp[idx].data.str.area,
 			       argp[idx].data.str.data);
 			trash.area[argp[idx].data.str.data] = 0;