diff --git a/t3/schema.py b/t3/schema.py
index 7c73b73f..007822a9 100644
--- a/t3/schema.py
+++ b/t3/schema.py
@@ -79,7 +79,7 @@ def check_shared_library_name(cls, value):
         """T3Options.shared_library_name validator"""
         if value is not None:
             for char in value:
-                if char not in VALID_CHARS:
+                if char not in VALID_CHARS + '/':
                     raise ValueError(f'The shared library name "{value}" contains an invalid character: {char}.\n'
                                      f'Only the following characters are allowed:\n{VALID_CHARS}')
         return value
@@ -89,7 +89,7 @@ def check_external_library_path(cls, value):
         """T3Options.external_library_path validator"""
         if value is not None:
             for char in value:
-                if char not in VALID_CHARS:
+                if char not in VALID_CHARS + '/':
                     raise ValueError(f'The external library path "{value}" contains an invalid character: {char}.\n'
                                      f'Only the following characters are allowed:\n{VALID_CHARS}')
         return value