diff --git a/ChangeLog.md b/ChangeLog.md
index 3743479..eaa36b8 100644
--- a/ChangeLog.md
+++ b/ChangeLog.md
@@ -6,6 +6,8 @@
 
 - Removed the exceptions from the library.
   ([#10](https://github.com/davep/gophermap/pull/10))
+- Added an optional strict mode (and, in doing so, added an exception back).
+  ([#12](https://github.com/davep/gophermap/pull/12))
 
 ## v0.2.0
 
diff --git a/src/gophermap/__init__.py b/src/gophermap/__init__.py
index 967250f..776644d 100644
--- a/src/gophermap/__init__.py
+++ b/src/gophermap/__init__.py
@@ -16,6 +16,7 @@
 
 ##############################################################################
 # Local imports.
+from .exceptions import GopherMapError
 from .gopher_map import GopherMap
 from .item import GopherItem
 from .item_type import ItemType
@@ -25,6 +26,7 @@
 __all__ = [
     "GopherItem",
     "GopherMap",
+    "GopherMapError",
     "ItemType",
 ]
 
diff --git a/src/gophermap/exceptions.py b/src/gophermap/exceptions.py
new file mode 100644
index 0000000..7b7970c
--- /dev/null
+++ b/src/gophermap/exceptions.py
@@ -0,0 +1,24 @@
+"""Provides exceptions for the Gopher map."""
+
+
+##############################################################################
+class GopherMapError(Exception):
+    """Base class for Gopher map errors."""
+
+
+##############################################################################
+class EmptyMap(GopherMapError):
+    """Raised when a Gopher map is empty."""
+
+
+##############################################################################
+class NoFields(GopherMapError):
+    """Raised when a Gopher item has no fields."""
+
+
+##############################################################################
+class UnknownItemType(GopherMapError):
+    """Raised when a Gopher item has an unknown type."""
+
+
+### exceptions.py ends here
diff --git a/src/gophermap/gopher_map.py b/src/gophermap/gopher_map.py
index 2502904..3e64ab7 100644
--- a/src/gophermap/gopher_map.py
+++ b/src/gophermap/gopher_map.py
@@ -8,6 +8,7 @@
 
 ##############################################################################
 # Local imports.
+from .exceptions import EmptyMap
 from .item import GopherItem
 
 ##############################################################################
@@ -19,17 +20,19 @@
 class GopherMap:
     """A class for parsing and holding a Gopher map."""
 
-    def __init__(self, map_text: str) -> None:
+    def __init__(self, map_text: str, strict: bool = False) -> None:
         """Initialise the Gopher map.
 
         Args:
             map_text: The text of the Gopher map.
+            strict: Whether to be strict about parsing the Gopher map.
         """
         self._raw = map_text
         """The raw text of the Gopher map."""
+        self._strict = strict
+        """Whether to be strict about parsing the Gopher map."""
 
-    @staticmethod
-    def _parse_map(map_text: str) -> Iterator[GopherItem]:
+    def _parse_map(self, map_text: str) -> Iterator[GopherItem]:
         """Parse the Gopher map text into a list of Gopher items.
 
         Args:
@@ -38,10 +41,12 @@ def _parse_map(map_text: str) -> Iterator[GopherItem]:
         Yields:
             Gopher items.
         """
+        if self._strict and not map_text:
+            raise EmptyMap("Gopher map is empty")
         for line in map_text.splitlines():
             if line == EOF:
                 break
-            yield GopherItem(line)
+            yield GopherItem(line, self._strict)
 
     @property
     def raw(self) -> str:
@@ -50,7 +55,13 @@ def raw(self) -> str:
 
     @cached_property
     def items(self) -> tuple[GopherItem, ...]:
-        """The list of Gopher items in the map."""
+        """The list of Gopher items in the map.
+
+        Raises:
+            EmptyMap: If the map is empty and strict mode is enabled.
+            NoFields: If the line is missing a tab character and strict mode is enabled.
+            UnknownItemType: If the item type is unknown and strict mode is enabled.
+        """
         return tuple(self._parse_map(self._raw))
 
 
diff --git a/src/gophermap/item.py b/src/gophermap/item.py
index b677b50..6fc9a46 100644
--- a/src/gophermap/item.py
+++ b/src/gophermap/item.py
@@ -2,6 +2,7 @@
 
 ##############################################################################
 # Local imports.
+from .exceptions import NoFields, UnknownItemType
 from .item_type import ItemType
 
 
@@ -9,11 +10,16 @@
 class GopherItem:
     """A class for holding an item in the Gopher map."""
 
-    def __init__(self, line: str) -> None:
+    def __init__(self, line: str, strict: bool = False) -> None:
         """Initialise the Gopher item.
 
         Args:
             line: The line of text from the Gopher map.
+            strict: Whether to be strict about parsing the Gopher item.
+
+        Raises:
+            NoFields: If the line is missing a tab character and strict mode is enabled.
+            UnknownItemType: If the item type is unknown and strict mode is enabled.
         """
         self._raw = line
         """The raw text of the Gopher item."""
@@ -29,6 +35,12 @@ def __init__(self, line: str) -> None:
         """The host of the Gopher item."""
         self._port = int(fields[3]) if len(fields) > 3 and fields[3].isdigit() else 70
         """The port of the Gopher item."""
+        # If we're in strict mode, let's do some harsh checks.
+        if strict:
+            if "\t" not in line:
+                raise NoFields(f"Line is missing a tab character: {line!r}")
+            if self._type is ItemType.UNKNOWN:
+                raise UnknownItemType(f"Unknown item type: {self._type!r}")
 
     @property
     def raw(self) -> str:
diff --git a/tests/test_gopher_map.py b/tests/test_gopher_map.py
index 8d04fd6..1741cfd 100644
--- a/tests/test_gopher_map.py
+++ b/tests/test_gopher_map.py
@@ -1,8 +1,12 @@
 """Tests for the GopherMap class."""
 
+##############################################################################
+# Pytest imports.
+from pytest import mark, raises
+
 ##############################################################################
 # Local imports.
-from gophermap import GopherMap
+from gophermap import GopherMap, GopherMapError
 from gophermap.item_type import ItemType
 
 
@@ -67,4 +71,19 @@ def test_allow_lines_without_tabs() -> None:
     assert gopher_map.items[0].port == 70
 
 
+##############################################################################
+@mark.parametrize(
+    "test_map",
+    [
+        "",
+        "Test\r\n.\r\n",
+        "!Hello\tworld\tlocalhost\r\n.\r\n",
+    ],
+)
+def test_strict_on_bad_map(test_map: str) -> None:
+    """Test that strict mode raises an error on a bad map."""
+    with raises(GopherMapError):
+        _ = GopherMap(test_map, strict=True).items
+
+
 ### test_gopher_map.py ends here