diff --git a/CHANGELOG.md b/CHANGELOG.md
index c5e05a91..9f5bb9bb 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -10,6 +10,8 @@ and this project adheres to [Semantic Versioning](http://semver.org/).
 
 ## Fixes
 
+- The `PusTmCreator` API only accepted 255 bytes of source data. It can now accept source
+  data with a size limited only by the size of `size_t`.
 - Important bugfix in CFDP PDU header format: The entity length field and the transaction sequence
   number fields stored the actual length of the field instead of the length minus 1 like specified
   in the CFDP standard.
diff --git a/src/fsfw/tmtcpacket/pus/tm/PusTmCreator.h b/src/fsfw/tmtcpacket/pus/tm/PusTmCreator.h
index 626d873e..19922b2f 100644
--- a/src/fsfw/tmtcpacket/pus/tm/PusTmCreator.h
+++ b/src/fsfw/tmtcpacket/pus/tm/PusTmCreator.h
@@ -40,7 +40,7 @@ struct PusTmParams {
               size_t dataLen)
       : secHeader(service, subservice, timeStamper), adapter(data, dataLen), sourceData(&adapter) {}
   PusTmSecHeader secHeader;
-  SerialBufferAdapter<uint8_t> adapter;
+  SerialBufferAdapter<size_t> adapter;
   const SerializeIF* sourceData = nullptr;
 };