diff --git a/doc/Makefile.am b/doc/Makefile.am
index e0316df0..1052f957 100644
--- a/doc/Makefile.am
+++ b/doc/Makefile.am
@@ -49,6 +49,7 @@ APIDOCS= \
 	nghttp2_hd_inflate_hd.rst \
 	nghttp2_hd_inflate_new.rst \
 	nghttp2_hd_inflate_new2.rst \
+	nghttp2_http2_strerror.rst \
 	nghttp2_is_fatal.rst \
 	nghttp2_nv_compare_name.rst \
 	nghttp2_option_del.rst \
diff --git a/lib/includes/nghttp2/nghttp2.h b/lib/includes/nghttp2/nghttp2.h
index 329a605d..f4c53fa6 100644
--- a/lib/includes/nghttp2/nghttp2.h
+++ b/lib/includes/nghttp2/nghttp2.h
@@ -3224,6 +3224,16 @@ nghttp2_pack_settings_payload(uint8_t *buf, size_t buflen,
  */
 NGHTTP2_EXTERN const char *nghttp2_strerror(int lib_error_code);
 
+/**
+ * @function
+ *
+ * Returns string representation of HTTP/2 error code |error_code|
+ * (e.g., ``PROTOCOL_ERROR`` is returned if ``error_code ==
+ * NGHTTP2_PROTOCOL_ERROR``).  If string representation is unknown for
+ * given |error_code|, this function returns string ``unknown``.
+ */
+NGHTTP2_EXTERN const char *nghttp2_http2_strerror(uint32_t error_code);
+
 /**
  * @function
  *
diff --git a/lib/nghttp2_helper.c b/lib/nghttp2_helper.c
index bdba797c..9f208519 100644
--- a/lib/nghttp2_helper.c
+++ b/lib/nghttp2_helper.c
@@ -451,3 +451,38 @@ uint8_t *nghttp2_cpymem(uint8_t *dest, const void *src, size_t len) {
 
   return dest + len;
 }
+
+const char *nghttp2_http2_strerror(uint32_t error_code) {
+  switch (error_code) {
+  case NGHTTP2_NO_ERROR:
+    return "NO_ERROR";
+  case NGHTTP2_PROTOCOL_ERROR:
+    return "PROTOCOL_ERROR";
+  case NGHTTP2_INTERNAL_ERROR:
+    return "INTERNAL_ERROR";
+  case NGHTTP2_FLOW_CONTROL_ERROR:
+    return "FLOW_CONTROL_ERROR";
+  case NGHTTP2_SETTINGS_TIMEOUT:
+    return "SETTINGS_TIMEOUT";
+  case NGHTTP2_STREAM_CLOSED:
+    return "STREAM_CLOSED";
+  case NGHTTP2_FRAME_SIZE_ERROR:
+    return "FRAME_SIZE_ERROR";
+  case NGHTTP2_REFUSED_STREAM:
+    return "REFUSED_STREAM";
+  case NGHTTP2_CANCEL:
+    return "CANCEL";
+  case NGHTTP2_COMPRESSION_ERROR:
+    return "COMPRESSION_ERROR";
+  case NGHTTP2_CONNECT_ERROR:
+    return "CONNECT_ERROR";
+  case NGHTTP2_ENHANCE_YOUR_CALM:
+    return "ENHANCE_YOUR_CALM";
+  case NGHTTP2_INADEQUATE_SECURITY:
+    return "INADEQUATE_SECURITY";
+  case NGHTTP2_HTTP_1_1_REQUIRED:
+    return "HTTP_1_1_REQUIRED";
+  default:
+    return "unknown";
+  }
+}
diff --git a/src/app_helper.cc b/src/app_helper.cc
index ecbe0b2f..ba84052b 100644
--- a/src/app_helper.cc
+++ b/src/app_helper.cc
@@ -62,43 +62,6 @@
 
 namespace nghttp2 {
 
-namespace {
-const char *strstatus(uint32_t error_code) {
-  switch (error_code) {
-  case NGHTTP2_NO_ERROR:
-    return "NO_ERROR";
-  case NGHTTP2_PROTOCOL_ERROR:
-    return "PROTOCOL_ERROR";
-  case NGHTTP2_INTERNAL_ERROR:
-    return "INTERNAL_ERROR";
-  case NGHTTP2_FLOW_CONTROL_ERROR:
-    return "FLOW_CONTROL_ERROR";
-  case NGHTTP2_SETTINGS_TIMEOUT:
-    return "SETTINGS_TIMEOUT";
-  case NGHTTP2_STREAM_CLOSED:
-    return "STREAM_CLOSED";
-  case NGHTTP2_FRAME_SIZE_ERROR:
-    return "FRAME_SIZE_ERROR";
-  case NGHTTP2_REFUSED_STREAM:
-    return "REFUSED_STREAM";
-  case NGHTTP2_CANCEL:
-    return "CANCEL";
-  case NGHTTP2_COMPRESSION_ERROR:
-    return "COMPRESSION_ERROR";
-  case NGHTTP2_CONNECT_ERROR:
-    return "CONNECT_ERROR";
-  case NGHTTP2_ENHANCE_YOUR_CALM:
-    return "ENHANCE_YOUR_CALM";
-  case NGHTTP2_INADEQUATE_SECURITY:
-    return "INADEQUATE_SECURITY";
-  case NGHTTP2_HTTP_1_1_REQUIRED:
-    return "HTTP_1_1_REQUIRED";
-  default:
-    return "UNKNOWN";
-  }
-}
-} // namespace
-
 namespace {
 const char *strsettingsid(int32_t id) {
   switch (id) {
@@ -335,7 +298,7 @@ void print_frame(print_type ptype, const nghttp2_frame *frame) {
   case NGHTTP2_RST_STREAM:
     print_frame_attr_indent();
     fprintf(outfile, "(error_code=%s(0x%02x))\n",
-            strstatus(frame->rst_stream.error_code),
+            nghttp2_http2_strerror(frame->rst_stream.error_code),
             frame->rst_stream.error_code);
     break;
   case NGHTTP2_SETTINGS:
@@ -364,7 +327,8 @@ void print_frame(print_type ptype, const nghttp2_frame *frame) {
     print_frame_attr_indent();
     fprintf(outfile, "(last_stream_id=%d, error_code=%s(0x%02x), "
                      "opaque_data(%u)=[%s])\n",
-            frame->goaway.last_stream_id, strstatus(frame->goaway.error_code),
+            frame->goaway.last_stream_id,
+            nghttp2_http2_strerror(frame->goaway.error_code),
             frame->goaway.error_code,
             static_cast<unsigned int>(frame->goaway.opaque_data_len),
             util::ascii_dump(frame->goaway.opaque_data,