diff --git a/beangulp/__init__.py b/beangulp/__init__.py
index eef15a7..b073b68 100644
--- a/beangulp/__init__.py
+++ b/beangulp/__init__.py
@@ -254,6 +254,8 @@ def _identify(ctx: "Ingest", src: str, failfast: bool, verbose: bool):
     log = utils.logger(verbose)
     errors = exceptions.ExceptionsTrap(log)
 
+    any_importer_found = False
+
     for filename in _walk(src, log):
         with errors:
             importer = identify.identify(ctx.importers, filename)
@@ -261,6 +263,8 @@ def _identify(ctx: "Ingest", src: str, failfast: bool, verbose: bool):
                 log("")  # Newline.
                 continue
 
+            any_importer_found = True
+
             # Signal processing of this document.
             log(" ...", nl=False)
 
@@ -277,6 +281,9 @@ def _identify(ctx: "Ingest", src: str, failfast: bool, verbose: bool):
     if errors:
         sys.exit(1)
 
+    if not any_importer_found:
+        sys.exit(100)
+
 
 def _importer(importer):
     """Check that the passed instance implements the Importer interface.
diff --git a/beangulp/tests/identify.rst b/beangulp/tests/identify.rst
index 7b8f31b..e649cb5 100644
--- a/beangulp/tests/identify.rst
+++ b/beangulp/tests/identify.rst
@@ -55,7 +55,7 @@ Test with an empty downloads directory:
 
   >>> r = run('identify', downloads)
   >>> r.exit_code
-  0
+  100
   >>> print(r.output)
 
 Add some documents: