diff --git a/lib/spdylay_frame.c b/lib/spdylay_frame.c
index dfd5b10..b7c7be8 100644
--- a/lib/spdylay_frame.c
+++ b/lib/spdylay_frame.c
@@ -1302,11 +1302,17 @@ ssize_t spdylay_frame_nv_offset(spdylay_frame_type type, uint16_t version)
 
 int spdylay_frame_nv_check_null(const char **nv)
 {
-  size_t i;
+  size_t i, j;
   for(i = 0; nv[i]; i += 2) {
     if(nv[i][0] == '\0' || nv[i+1] == NULL) {
       return 0;
     }
+    for(j = 0; nv[i][j]; ++j) {
+      unsigned char c = nv[i][j];
+      if(c < 0x20 || c > 0x7e) {
+        return 0;
+      }
+    }
   }
   return 1;
 }
diff --git a/lib/spdylay_frame.h b/lib/spdylay_frame.h
index 8843757..f6373ff 100644
--- a/lib/spdylay_frame.h
+++ b/lib/spdylay_frame.h
@@ -794,7 +794,8 @@ void spdylay_frame_iv_sort(spdylay_settings_entry *iv, size_t niv);
 ssize_t spdylay_frame_nv_offset(spdylay_frame_type type, uint16_t version);
 
 /*
- * Checks names are not empty string and values are not NULL.
+ * Checks names are not empty string and do not contain control
+ * characters and values are not NULL.
  *
  * This function returns nonzero if it succeeds, or 0.
  */
diff --git a/tests/main.c b/tests/main.c
index e2bfc64..33b62c5 100644
--- a/tests/main.c
+++ b/tests/main.c
@@ -226,6 +226,8 @@ int main(int argc, char* argv[])
                    test_spdylay_frame_unpack_nv_last_empty_value_spdy3) ||
       !CU_add_test(pSuite, "frame_nv_set_origin",
                    test_spdylay_frame_nv_set_origin) ||
+      !CU_add_test(pSuite, "frame_nv_check_null",
+                   test_spdylay_frame_nv_check_null) ||
       !CU_add_test(pSuite, "stream_add_pushed_stream",
                    test_spdylay_stream_add_pushed_stream) ||
       !CU_add_test(pSuite, "client_cert_vector_find",
diff --git a/tests/spdylay_frame_test.c b/tests/spdylay_frame_test.c
index 343df38..22c1f20 100644
--- a/tests/spdylay_frame_test.c
+++ b/tests/spdylay_frame_test.c
@@ -986,3 +986,16 @@ void test_spdylay_frame_nv_set_origin(void)
   CU_ASSERT(SPDYLAY_ERR_INVALID_ARGUMENT ==
             spdylay_frame_nv_set_origin((char**)nv5, &origin));
 }
+
+void test_spdylay_frame_nv_check_null(void)
+{
+  const char *headers1[] = { "path", "/", "host", "a", NULL };
+  const char *headers2[] = { "", "/", "host", "a", NULL };
+  const char *headers3[] = { "path", "/", "host\x01", "a", NULL };
+  const char *headers4[] = { "path", "/", "host", NULL, NULL };
+
+  CU_ASSERT(spdylay_frame_nv_check_null(headers1));
+  CU_ASSERT(0 == spdylay_frame_nv_check_null(headers2));
+  CU_ASSERT(0 == spdylay_frame_nv_check_null(headers3));
+  CU_ASSERT(0 == spdylay_frame_nv_check_null(headers4));
+}
diff --git a/tests/spdylay_frame_test.h b/tests/spdylay_frame_test.h
index 555dbe0..ed66a57 100644
--- a/tests/spdylay_frame_test.h
+++ b/tests/spdylay_frame_test.h
@@ -55,5 +55,6 @@ void test_spdylay_frame_unpack_nv_check_name_spdy3(void);
 void test_spdylay_frame_unpack_nv_last_empty_value_spdy2(void);
 void test_spdylay_frame_unpack_nv_last_empty_value_spdy3(void);
 void test_spdylay_frame_nv_set_origin(void);
+void test_spdylay_frame_nv_check_null(void);
 
 #endif /* SPDYLAY_FRAME_TEST_H */