diff --git a/src/ralph/backends/data/async_lrs.py b/src/ralph/backends/data/async_lrs.py
index 24b363470..1e767777b 100644
--- a/src/ralph/backends/data/async_lrs.py
+++ b/src/ralph/backends/data/async_lrs.py
@@ -5,7 +5,7 @@
 from urllib.parse import ParseResult, parse_qs, urljoin, urlparse
 
 from httpx import AsyncClient, HTTPError, HTTPStatusError, RequestError
-from pydantic import AnyHttpUrl, parse_obj_as
+from pydantic import AnyHttpUrl, PositiveInt, parse_obj_as
 
 from ralph.backends.data.base import (
     AsyncWritable,
@@ -76,8 +76,8 @@ async def read(  # noqa: PLR0913
         chunk_size: Optional[int] = None,
         raw_output: bool = False,
         ignore_errors: bool = False,
-        prefetch: Optional[int] = None,
-        max_statements: Optional[int] = None,
+        prefetch: Optional[PositiveInt] = None,
+        max_statements: Optional[PositiveInt] = None,
     ) -> Union[AsyncIterator[bytes], AsyncIterator[dict]]:
         """Get statements from LRS `target` endpoint.
 
@@ -99,12 +99,8 @@ async def read(  # noqa: PLR0913
             ignore_errors (bool): If `True`, errors during the read operation
                 are ignored and logged. If `False` (default), a `BackendException`
                 is raised if an error occurs.
-            prefetch: The number of records to prefetch (queue) while yielding.
-                If `prefetch` is `None` or `0` it defaults to `1` - no records are
-                prefetched.
-                If `prefetch` is less than zero, all records are prefetched.
-                Caution: setting `prefetch<0` might potentially lead to large amounts
-                of API calls and to the memory filling up.
+            prefetch (int): The number of records to prefetch (queue) while yielding.
+                If `prefetch` is `None` it defaults to `1` - no records are prefetched.
             max_statements: The maximum number of statements to yield.
         """
         statements = super().read(
diff --git a/src/ralph/backends/data/lrs.py b/src/ralph/backends/data/lrs.py
index 9eaebfbd0..01f291fb9 100644
--- a/src/ralph/backends/data/lrs.py
+++ b/src/ralph/backends/data/lrs.py
@@ -5,7 +5,7 @@
 from urllib.parse import ParseResult, parse_qs, urljoin, urlparse
 
 from httpx import Client, HTTPError, HTTPStatusError, RequestError
-from pydantic import AnyHttpUrl, BaseModel, Field, parse_obj_as
+from pydantic import AnyHttpUrl, BaseModel, Field, PositiveInt, parse_obj_as
 
 from ralph.backends.data.base import (
     BaseDataBackend,
@@ -117,7 +117,7 @@ def read(  # noqa: PLR0913
         chunk_size: Optional[int] = None,
         raw_output: bool = False,
         ignore_errors: bool = False,
-        max_statements: Optional[int] = None,
+        max_statements: Optional[PositiveInt] = None,
     ) -> Union[Iterator[bytes], Iterator[dict]]:
         """Get statements from LRS `target` endpoint.
 
diff --git a/tests/backends/data/test_async_lrs.py b/tests/backends/data/test_async_lrs.py
index 6dd4377a3..e504b287b 100644
--- a/tests/backends/data/test_async_lrs.py
+++ b/tests/backends/data/test_async_lrs.py
@@ -708,7 +708,7 @@ async def _simulate_slow_processing():
     without_prefetch_duration = time.time() - time_1
 
     time_2 = time.time()
-    async for _ in backend.read(target=targets[0], chunk_size=chunk_size, prefetch=-1):
+    async for _ in backend.read(target=targets[0], chunk_size=chunk_size, prefetch=100):
         await _simulate_slow_processing()
     prefetch_duration = time.time() - time_2