diff --git a/src/components/gpu.c b/src/components/gpu.c
index 9f7c417..7a9cd57 100644
--- a/src/components/gpu.c
+++ b/src/components/gpu.c
@@ -134,6 +134,11 @@ void nni_gpu_set(nni_gpu *gpu, void *_, nn_component *component, nn_computer *co
         return;
     }
 
+    if(!nn_unicode_validate(s)) {
+        nn_setCError(computer, "invalid utf-8");
+        return;
+    }
+
     int current = 0;
     while(s[current]) {
         int codepoint = nn_unicode_codepointAt(s, current);
@@ -294,6 +299,10 @@ void nni_gpu_fill(nni_gpu *gpu, void *_, nn_component *component, nn_computer *c
         nn_setCError(computer, "bad argument #5 (character expected)");
         return;
     }
+    if(!nn_unicode_validate(s)) {
+        nn_setCError(computer, "invalid utf-8");
+        return;
+    }
 
     int codepoint = nn_unicode_codepointAt(s, 0);
 
diff --git a/src/testLuaArch.c b/src/testLuaArch.c
index 103a351..dc21ebd 100644
--- a/src/testLuaArch.c
+++ b/src/testLuaArch.c
@@ -483,6 +483,7 @@ int testLuaArch_unicode_char(lua_State *L) {
         if(!lua_isinteger(L, idx)) {
             nn_free(codepoints);
             luaL_argerror(L, idx, "integer expected");
+            return 0;
         }
         codepoints[i] = lua_tointeger(L, idx);
     }