diff --git a/gh-md-toc b/gh-md-toc
index ed53a51..8714945 100755
--- a/gh-md-toc
+++ b/gh-md-toc
@@ -77,21 +77,29 @@ gh_toc_md2html() {
     fi
 
     # echo $URL 1>&2
+    # append the HTTP status code as the last line of the output, so API
+    # errors are detected by status rather than by the rendered markdown
     OUTPUT=$(curl -s \
         --user-agent "$gh_user_agent" \
         --data-binary @"$gh_tmp_file_md" \
         -H "Content-Type:text/plain" \
         -H "$AUTHORIZATION" \
+        -w '\n%{http_code}' \
         "$URL")
     local curl_status=$?
+    local http_code=${OUTPUT##*$'\n'}
+    OUTPUT=${OUTPUT%$'\n'*}
 
     rm -f "${gh_file_md}~~"
 
     if [ "$curl_status" != "0" ]; then
         echo "XXNetworkErrorXX"
-    fi
-    if [ "$(echo "${OUTPUT}" | awk '/API rate limit exceeded/')" != "" ]; then
+    elif [ "$http_code" = "401" ]; then
+        echo "XXBadCredentialsXX"
+    elif [ "$http_code" != "200" ] && [ "$(echo "${OUTPUT}" | awk '/API rate limit exceeded/')" != "" ]; then
         echo "XXRateLimitXX"
+    elif [ "$http_code" != "200" ]; then
+        echo "XXApiErrorXX ${http_code}"
     else
         echo "${OUTPUT}"
     fi
@@ -161,13 +169,26 @@ gh_toc(){
              echo "Parsing local markdown file requires access to github API"
              echo "Please make sure curl is installed and check your network connectivity"
              exit 1
-        fi
-        if [ "$rawhtml" == "XXRateLimitXX" ]; then
+        elif [ "$rawhtml" == "XXRateLimitXX" ]; then
              echo "Parsing local markdown file requires access to github API"
              echo "Error: You exceeded the hourly limit. See: https://developer.github.com/v3/#rate-limiting"
              TOKEN_FILE="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)/token.txt"
              echo "or place GitHub auth token here: ${TOKEN_FILE}"
              exit 1
+        elif [ "$rawhtml" == "XXBadCredentialsXX" ]; then
+             echo "Parsing local markdown file requires access to github API"
+             echo "Error: GitHub API rejected the auth token (HTTP 401 Bad credentials)"
+             if [ -n "$GH_TOC_TOKEN" ]; then
+                 echo "Check the GitHub auth token in the GH_TOC_TOKEN environment variable"
+             else
+                 TOKEN_FILE="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)/token.txt"
+                 echo "Check the GitHub auth token here: ${TOKEN_FILE}"
+             fi
+             exit 1
+        elif [[ "$rawhtml" == "XXApiErrorXX "* ]]; then
+             echo "Parsing local markdown file requires access to github API"
+             echo "Error: GitHub API request failed (HTTP ${rawhtml#XXApiErrorXX })"
+             exit 1
         fi
         local toc
         toc=$(echo "$rawhtml" | gh_toc_grab "$gh_src_copy" "$indent" "$depth" "$numbered")
diff --git a/tests/test directory/test_api_error_text.md b/tests/test directory/test_api_error_text.md
new file mode 100644
index 0000000..eb46f7e
--- /dev/null
+++ b/tests/test directory/test_api_error_text.md	
@@ -0,0 +1,7 @@
+# Bad credentials
+
+Docs that mention GitHub API errors must still render.
+
+## API rate limit exceeded
+
+Blabla...
diff --git a/tests/tests.bats b/tests/tests.bats
index 86ab465..6d0b53f 100755
--- a/tests/tests.bats
+++ b/tests/tests.bats
@@ -245,6 +245,23 @@ test_help() {
     assert_equal "${lines[3]}"   "Please make sure curl is installed and check your network connectivity"
 }
 
+@test "Error for local file with invalid GitHub token" {
+    GH_TOC_TOKEN=invalid run $BATS_TEST_DIRNAME/../gh-md-toc tests/test\ directory/test_plussign.md
+    assert_fail
+
+    assert_equal "${lines[2]}"   "Parsing local markdown file requires access to github API"
+    assert_equal "${lines[3]}"   "Error: GitHub API rejected the auth token (HTTP 401 Bad credentials)"
+    assert_equal "${lines[4]}"   "Check the GitHub auth token in the GH_TOC_TOKEN environment variable"
+}
+
+@test "TOC for local file mentioning API error messages" {
+    run $BATS_TEST_DIRNAME/../gh-md-toc tests/test\ directory/test_api_error_text.md
+    assert_success
+
+    assert_equal "${lines[2]}"   "* [Bad credentials](#bad-credentials)"
+    assert_equal "${lines[3]}"   "   * [API rate limit exceeded](#api-rate-limit-exceeded)"
+}
+
 @test "TOC with depth for local file, #25" {
     run $BATS_TEST_DIRNAME/../gh-md-toc --depth 2 tests/test\ directory/test_depth.md
     assert_success