diff --git a/src/caoscrawler/identifiable_adapters.py b/src/caoscrawler/identifiable_adapters.py
index 6399bd4937dc3503cacdf55aab869a9c917e6e38..d4c2b1d04316946dc28fec15489e0dc390cb9dd3 100644
--- a/src/caoscrawler/identifiable_adapters.py
+++ b/src/caoscrawler/identifiable_adapters.py
@@ -52,11 +52,11 @@ def convert_value(value):
         return str(value.id)
     elif isinstance(value, datetime):
         return value.isoformat()
-    elif isinstance(value, str):
+    elif type(value) == str:
         # replace single quotes, otherwise they may break the queries
-        return str(value.replace("'", "\'"))
+        return value.replace("\'", "\\'")
     else:
-        return value
+        return f"{value}"
 
 
 class IdentifiableAdapter(metaclass=ABCMeta):