diff --git a/CHANGES b/CHANGES
index 76422d6035..22bd59e630 100644
--- a/CHANGES
+++ b/CHANGES
@@ -1,4 +1,13 @@
 
+3.1.0-dev.143 | 2019-09-24 10:23:24 -0700
+
+  * Simplify reassembly code using DataBlockList::LastBlock() (Jon Siwek, Corelight)
+
+  * Fix DataBlockList::DataSize() (Jon Siwek, Corelight)
+
+    Parameters got filled opposite to what they were supposed to be and
+    also didn't consider cutoffs that land in the middle of a block.
+
 3.1.0-dev.141 | 2019-09-24 10:31:50 +0000
 
   * Reorganize reassembly data structures. This replaces the previous
diff --git a/VERSION b/VERSION
index e6c39b46be..7565ce859e 100644
--- a/VERSION
+++ b/VERSION
@@ -1 +1 @@
-3.1.0-dev.141
+3.1.0-dev.143
diff --git a/src/Frag.cc b/src/Frag.cc
index 4d1f7ace47..a39f2ea33e 100644
--- a/src/Frag.cc
+++ b/src/Frag.cc
@@ -205,7 +205,7 @@ void FragReassembler::BlockInserted(DataBlockMap::const_iterator /* it */)
 		++next;
 		}
 
-	const auto& last = std::prev(block_list.End())->second;
+	const auto& last = block_list.LastBlock();
 
 	if ( next != block_list.End() )
 		{
diff --git a/src/analyzer/protocol/tcp/TCP_Reassembler.cc b/src/analyzer/protocol/tcp/TCP_Reassembler.cc
index e5b1250a05..947ebcd433 100644
--- a/src/analyzer/protocol/tcp/TCP_Reassembler.cc
+++ b/src/analyzer/protocol/tcp/TCP_Reassembler.cc
@@ -68,7 +68,7 @@ void TCP_Reassembler::Done()
 		{ // Record any undelivered data.
 		if ( ! block_list.Empty() )
 			{
-			auto last_block = std::prev(block_list.End())->second;
+			const auto& last_block = block_list.LastBlock();
 
 			if ( last_reassem_seq < last_block.upper )
 				RecordToSeq(last_reassem_seq, last_block.upper,
@@ -91,7 +91,7 @@ uint64_t TCP_Reassembler::NumUndeliveredBytes() const
 	if ( block_list.Empty() )
 		return 0;
 
-	auto last_block = std::prev(block_list.End())->second;
+	const auto& last_block = block_list.LastBlock();
 	return last_block.upper - last_reassem_seq;
 	}
 
@@ -289,7 +289,7 @@ void TCP_Reassembler::MatchUndelivered(uint64_t up_to_seq, bool use_last_upper)
 	if ( block_list.Empty() || ! rule_matcher )
 		return;
 
-	const auto& last_block = std::prev(block_list.End())->second;
+	const auto& last_block = block_list.LastBlock();
 
 	if ( use_last_upper )
 		up_to_seq = last_block.upper;
diff --git a/src/file_analysis/FileReassembler.cc b/src/file_analysis/FileReassembler.cc
index 6eb5453beb..ffc2fda54f 100644
--- a/src/file_analysis/FileReassembler.cc
+++ b/src/file_analysis/FileReassembler.cc
@@ -29,7 +29,7 @@ uint64_t FileReassembler::Flush()
 	if ( block_list.Empty() )
 		return 0;
 
-	const auto& last_block = std::prev(block_list.End())->second;
+	const auto& last_block = block_list.LastBlock();
 
 	// This is expected to call back into FileReassembler::Undelivered().
 	flushing = true;