diff --git a/helper/build_config b/helper/build_config
index 919540df..e1c351af 100755
--- a/helper/build_config
+++ b/helper/build_config
@@ -102,6 +102,7 @@ log_debug "      and: move ${tt_tmp_output_file} ${output_file}"
 # We need to use «readlink -f» so that we do not destroy any symlink pointing
 # to the real file, which we were previously preserving while using «cat».
 if "$TT_WRAPPER" "${input_file}" > "${tt_tmp_output_file}" 2>/dev/null &&
+   ! grep -q -E '^file error' "${tt_tmp_output_file}" 2>/dev/null &&
    move "${tt_tmp_output_file}" "$(readlink -f "${output_file}")" ; then
   log_info "Generating ${output_file}: OK"
   RC=0
@@ -109,6 +110,11 @@ else
   log_error "Generating ${output_file} based on ${input_file}: FAILED"
   RC=1
 
+  if [[ -r "${tt_tmp_output_file}" ]] && grep -q -E '^file error' "${tt_tmp_output_file}" ; then
+    log_error "from generated file:"
+    log_error "  $(grep -E '^file error' "${tt_tmp_output_file}")"
+  fi
+
   log_info "NOTE: Check those files for valid syntax and encoding:"
   for f in "${input_file}" ${host_conf:-} ${local_conf:-} "$NGCPCTL_CONFIG" "${NETWORK_CONFIG:-}" ${EXTRA_CONFIG_FILES:-} "$CONSTANTS_CONFIG" ; do
     [ -r "$f" ] && log_info "$f"
diff --git a/t/fixtures/output/bad-syntax.txt b/t/fixtures/output/bad-syntax.txt
new file mode 100644
index 00000000..7ee962dc
--- /dev/null
+++ b/t/fixtures/output/bad-syntax.txt
@@ -0,0 +1,2 @@
+file error - parse error - input file handle line 1: unexpected end of directive
+  [% IF %]
\ No newline at end of file
diff --git a/t/fixtures/repos/templates/etc/bad-syntax.txt.tt2 b/t/fixtures/repos/templates/etc/bad-syntax.txt.tt2
new file mode 100644
index 00000000..9da11897
--- /dev/null
+++ b/t/fixtures/repos/templates/etc/bad-syntax.txt.tt2
@@ -0,0 +1 @@
+[% IF %]
diff --git a/t/test_ngcpcfg_build_syntax.py b/t/test_ngcpcfg_build_syntax.py
new file mode 100644
index 00000000..6c8a3e10
--- /dev/null
+++ b/t/test_ngcpcfg_build_syntax.py
@@ -0,0 +1,60 @@
+#!/usr/bin/env py.test-3
+
+import filecmp
+import os
+import pytest
+import re
+import tempfile
+import sys
+
+
+@pytest.mark.tt_46601
+def test_bad_syntax(ngcpcfgcli, tmpdir):
+    tmpdir = tempfile.mkdtemp(prefix='ngcp-', suffix='-pytest-output')
+    out = ngcpcfgcli("build", "--ignore-branch-check",
+                     "/etc/bad-syntax.txt",
+                     env={
+                         'NGCP_BASE_TT2': os.getcwd(),
+                         'NGCP_SOCKETFILE': '/tmp/ngcpcfg.socket',
+                         'OUTPUT_DIRECTORY': tmpdir,
+                         'NGCPCFG': 'fixtures/ngcpcfg_carrier.cfg',
+                     })
+
+    # debug, only printed in logs in case of error
+    print("stdout:")
+    print(out.stdout.replace("\\n", "\n"))
+    print("stderr:")
+    print(out.stderr.replace("\\n", "\n"))
+
+    regex1 = re.compile(r"NOTE: Check those files for valid syntax and "
+                        "encoding.*etc/bad-syntax\.txt\.tt2.*or inspecting "
+                        "temporary /tmp/ngcpcfg\.bad-syntax\.txt\.")
+    assert re.search(regex1, out.stdout)
+
+    regex2 = re.compile(r"Error: Generating /tmp/ngcp-.*-pytest-output.*"
+                        "/etc/bad-syntax.txt based on .*"
+                        "/etc/bad-syntax\.txt\.tt2: FAILED")
+    assert re.search(regex2, out.stderr)
+
+    regex3 = re.compile(r"Error:   file error - parse error - input file "
+                        "handle line 1: unexpected end of directive")
+    assert re.search(regex3, out.stderr)
+
+    output_file = os.path.join(tmpdir, "etc/bad-syntax.txt")
+    test_file = "fixtures/output/bad-syntax.txt"
+    output_temp_file = re.sub(r".* or inspecting temporary ", "", out.stdout)
+    output_temp_file = re.sub(r"\\.*", "", output_temp_file)
+    # debug
+    print("Output temp file: '%s'" % (output_temp_file))
+
+    assert not os.path.exists(output_file)
+    assert os.path.exists(output_temp_file)
+    assert os.path.exists(test_file)
+
+    # debug
+    if not filecmp.cmp(output_temp_file, test_file):
+        print("output_temp_file:")
+        print(open(output_temp_file).read())
+        print("test_file:")
+        print(open(test_file).read())
+    assert filecmp.cmp(output_temp_file, test_file)