diff --git a/lib/nghttp2_frame.c b/lib/nghttp2_frame.c
index d365bb4f..82e1d4dd 100644
--- a/lib/nghttp2_frame.c
+++ b/lib/nghttp2_frame.c
@@ -721,17 +721,13 @@ ssize_t nghttp2_frame_nv_offset(const uint8_t *head)
 
 int nghttp2_frame_nv_check_null(const char **nv)
 {
-  size_t i, j;
+  size_t i;
   for(i = 0; nv[i]; i += 2) {
-    if(nv[i][0] == '\0' || nv[i+1] == NULL) {
+    if(nv[i+1] == NULL ||
+       !nghttp2_check_header_name_nocase((const uint8_t*)nv[i],
+                                         strlen(nv[i]))) {
       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/nghttp2_frame.h b/lib/nghttp2_frame.h
index 15366f4c..e29ae578 100644
--- a/lib/nghttp2_frame.h
+++ b/lib/nghttp2_frame.h
@@ -623,7 +623,8 @@ void nghttp2_nv_array_del(nghttp2_nv *nva);
 
 /*
  * Checks names are not empty string and do not contain control
- * characters and values are not NULL.
+ * characters and values are not NULL. This function allows captital
+ * alphabet letters in name.
  *
  * This function returns nonzero if it succeeds, or 0.
  */
diff --git a/lib/nghttp2_hd.c b/lib/nghttp2_hd.c
index 0f75ded2..4c993d3b 100644
--- a/lib/nghttp2_hd.c
+++ b/lib/nghttp2_hd.c
@@ -914,6 +914,10 @@ ssize_t nghttp2_hd_inflate_hd(nghttp2_hd_context *inflater,
         rv = NGHTTP2_ERR_HEADER_COMP;
         goto fail;
       }
+      if(!nghttp2_check_header_name(in, namelen)) {
+        rv = NGHTTP2_ERR_HEADER_COMP;
+        goto fail;
+      }
       nv.name = in;
       in += namelen;
       in = decode_length(&valuelen, in, last, 8);
@@ -1005,6 +1009,10 @@ ssize_t nghttp2_hd_inflate_hd(nghttp2_hd_context *inflater,
         rv = NGHTTP2_ERR_HEADER_COMP;
         goto fail;
       }
+      if(!nghttp2_check_header_name(in, namelen)) {
+        rv = NGHTTP2_ERR_HEADER_COMP;
+        goto fail;
+      }
       nv.name = in;
       in += namelen;
       in = decode_length(&subindex, in, last, 8);
diff --git a/lib/nghttp2_helper.c b/lib/nghttp2_helper.c
index 6dae649e..90ac00f3 100644
--- a/lib/nghttp2_helper.c
+++ b/lib/nghttp2_helper.c
@@ -24,6 +24,7 @@
  */
 #include "nghttp2_helper.h"
 
+#include <assert.h>
 #include <string.h>
 
 #include "nghttp2_net.h"
@@ -122,6 +123,71 @@ int nghttp2_should_send_window_update(int32_t local_window_size,
   return recv_window_size >= local_window_size / 2;
 }
 
+static int VALID_HD_NAME_CHARS[] = {
+ -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
+ -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
+ 1 /* ! */,
+ -1,
+ 1 /* # */, 1 /* $ */, 1 /* % */, 1 /* & */, 1 /* ' */,
+ -1, -1,
+ 1 /* * */, 1 /* + */,
+ -1,
+ 1 /* - */, 1 /* . */,
+ -1,
+ 1 /* 0 */, 1 /* 1 */, 1 /* 2 */, 1 /* 3 */, 1 /* 4 */, 1 /* 5 */,
+ 1 /* 6 */, 1 /* 7 */, 1 /* 8 */, 1 /* 9 */,
+ -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
+ -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
+ 1 /* ^ */, 1 /* _ */, 1 /* ` */, 1 /* a */, 1 /* b */, 1 /* c */, 1 /* d */,
+ 1 /* e */, 1 /* f */, 1 /* g */, 1 /* h */, 1 /* i */, 1 /* j */, 1 /* k */,
+ 1 /* l */, 1 /* m */, 1 /* n */, 1 /* o */, 1 /* p */, 1 /* q */, 1 /* r */,
+ 1 /* s */, 1 /* t */, 1 /* u */, 1 /* v */, 1 /* w */, 1 /* x */, 1 /* y */,
+ 1 /* z */,
+ -1,
+ 1 /* | */,
+ -1,
+ 1 /* ~ */,
+ -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
+ -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
+ -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
+ -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
+ -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
+ -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
+ -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1
+};
+
+static int check_header_name(const uint8_t *name, size_t len, int nocase)
+{
+  const uint8_t *last;
+  if(len == 0) {
+    return 0;
+  }
+  if(*name == ':') {
+    if(len == 1) {
+      return 0;
+    }
+    ++name;
+    --len;
+  }
+  for(last = name + len; name != last; ++name) {
+    if(nocase && 'A' <= *name && *name <= 'Z') continue;
+    if(VALID_HD_NAME_CHARS[*name] == -1) {
+      return 0;
+    }
+  }
+  return 1;
+}
+
+int nghttp2_check_header_name(const uint8_t *name, size_t len)
+{
+  return check_header_name(name, len, 0);
+}
+
+int nghttp2_check_header_name_nocase(const uint8_t *name, size_t len)
+{
+  return check_header_name(name, len, 1);
+}
+
 const char* nghttp2_strerror(int error_code)
 {
   switch(error_code) {
diff --git a/lib/nghttp2_helper.h b/lib/nghttp2_helper.h
index 3439dcf5..40a5d176 100644
--- a/lib/nghttp2_helper.h
+++ b/lib/nghttp2_helper.h
@@ -116,4 +116,19 @@ int nghttp2_adjust_local_window_size(int32_t *local_window_size_ptr,
 int nghttp2_should_send_window_update(int32_t local_window_size,
                                       int32_t recv_window_size);
 
+/*
+ * Checks the header name in |name| with |len| bytes is valid.
+ *
+ * This function returns nonzero if it succeeds, or 0.
+ */
+int nghttp2_check_header_name(const uint8_t *name, size_t len);
+
+/*
+ * Checks the header name in |name| with |len| bytes is valid. This
+ * function accepts also characters in [A-Z].
+ *
+ * This function returns nonzero if it succeeds, or 0.
+ */
+int nghttp2_check_header_name_nocase(const uint8_t *name, size_t len);
+
 #endif /* NGHTTP2_HELPER_H */
diff --git a/tests/main.c b/tests/main.c
index 78383991..23a11110 100644
--- a/tests/main.c
+++ b/tests/main.c
@@ -240,7 +240,9 @@ int main(int argc, char* argv[])
                    test_nghttp2_hd_deflate_inflate) ||
       !CU_add_test(pSuite, "gzip_inflate", test_nghttp2_gzip_inflate) ||
       !CU_add_test(pSuite, "adjust_local_window_size",
-                   test_nghttp2_adjust_local_window_size)
+                   test_nghttp2_adjust_local_window_size) ||
+      !CU_add_test(pSuite, "check_header_name",
+                   test_nghttp2_check_header_name)
       ) {
      CU_cleanup_registry();
      return CU_get_error();
diff --git a/tests/nghttp2_frame_test.c b/tests/nghttp2_frame_test.c
index beb1ec1b..b01e6dfd 100644
--- a/tests/nghttp2_frame_test.c
+++ b/tests/nghttp2_frame_test.c
@@ -85,7 +85,7 @@ void test_nghttp2_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 };
+  const char *headers4[] = { "PATH", "/", "host", NULL, NULL };
 
   CU_ASSERT(nghttp2_frame_nv_check_null(headers1));
   CU_ASSERT(0 == nghttp2_frame_nv_check_null(headers2));
diff --git a/tests/nghttp2_helper_test.c b/tests/nghttp2_helper_test.c
index 83ecfb71..f038809b 100644
--- a/tests/nghttp2_helper_test.c
+++ b/tests/nghttp2_helper_test.c
@@ -73,3 +73,32 @@ void test_nghttp2_adjust_local_window_size(void)
   CU_ASSERT(100 == local_window_size);
   CU_ASSERT(50 == recv_window_size);
 }
+
+static int check_header_name(const char *s)
+{
+  return nghttp2_check_header_name((const uint8_t*)s, strlen(s));
+}
+
+static int check_header_name_nocase(const char *s)
+{
+  return nghttp2_check_header_name_nocase((const uint8_t*)s, strlen(s));
+}
+
+void test_nghttp2_check_header_name(void)
+{
+  CU_ASSERT(check_header_name(":path"));
+  CU_ASSERT(check_header_name("path"));
+  CU_ASSERT(check_header_name("!#$%&'*+-.^_`|~"));
+  CU_ASSERT(!check_header_name(":PATH"));
+  CU_ASSERT(!check_header_name("path:"));
+  CU_ASSERT(!check_header_name(""));
+  CU_ASSERT(!check_header_name(":"));
+
+  CU_ASSERT(check_header_name_nocase(":path"));
+  CU_ASSERT(check_header_name_nocase("path"));
+  CU_ASSERT(check_header_name_nocase("!#$%&'*+-.^_`|~"));
+  CU_ASSERT(check_header_name_nocase(":PATH"));
+  CU_ASSERT(!check_header_name_nocase("path:"));
+  CU_ASSERT(!check_header_name_nocase(""));
+  CU_ASSERT(!check_header_name_nocase(":"));
+}
diff --git a/tests/nghttp2_helper_test.h b/tests/nghttp2_helper_test.h
index c4940d2c..a7699cf9 100644
--- a/tests/nghttp2_helper_test.h
+++ b/tests/nghttp2_helper_test.h
@@ -26,5 +26,6 @@
 #define NGHTTP2_HELPER_TEST_H
 
 void test_nghttp2_adjust_local_window_size(void);
+void test_nghttp2_check_header_name(void);
 
 #endif /* NGHTTP2_HELPER_TEST_H */
diff --git a/tests/nghttp2_session_test.c b/tests/nghttp2_session_test.c
index 87e2e5de..59130416 100644
--- a/tests/nghttp2_session_test.c
+++ b/tests/nghttp2_session_test.c
@@ -1606,7 +1606,7 @@ void test_nghttp2_submit_response(void)
 {
   nghttp2_session *session;
   nghttp2_session_callbacks callbacks;
-  const char *nv[] = { "Content-Length", "1024", NULL };
+  const char *nv[] = { "content-length", "1024", NULL };
   nghttp2_data_provider data_prd;
   my_user_data ud;
   nghttp2_outbound_item *item;
@@ -1632,7 +1632,7 @@ void test_nghttp2_submit_response_without_data(void)
   nghttp2_session *session;
   nghttp2_session_callbacks callbacks;
   accumulator acc;
-  const char *nv[] = { ":Version", "HTTP/1.1", NULL };
+  const char *nv[] = { ":version", "HTTP/1.1", NULL };
   nghttp2_data_provider data_prd = {{-1}, NULL};
   nghttp2_outbound_item *item;
   my_user_data ud;
@@ -1665,7 +1665,7 @@ void test_nghttp2_submit_request_with_data(void)
 {
   nghttp2_session *session;
   nghttp2_session_callbacks callbacks;
-  const char *nv[] = { ":Version", "HTTP/1.1", NULL };
+  const char *nv[] = { ":version", "HTTP/1.1", NULL };
   nghttp2_data_provider data_prd;
   my_user_data ud;
   nghttp2_outbound_item *item;
@@ -1691,7 +1691,7 @@ void test_nghttp2_submit_request_without_data(void)
   nghttp2_session *session;
   nghttp2_session_callbacks callbacks;
   accumulator acc;
-  const char *nv[] = { ":Version", "HTTP/1.1", NULL };
+  const char *nv[] = { ":version", "HTTP/1.1", NULL };
   nghttp2_data_provider data_prd = {{-1}, NULL};
   nghttp2_outbound_item *item;
   my_user_data ud;
@@ -1842,7 +1842,7 @@ void test_nghttp2_submit_headers(void)
 {
   nghttp2_session *session;
   nghttp2_session_callbacks callbacks;
-  const char *nv[] = { ":Version", "HTTP/1.1", NULL };
+  const char *nv[] = { ":version", "HTTP/1.1", NULL };
   my_user_data ud;
   nghttp2_outbound_item *item;
   nghttp2_stream *stream;