diff --git a/pyagentspec/constraints/constraints.txt b/pyagentspec/constraints/constraints.txt
index 23ab31e4..cd063a4d 100644
--- a/pyagentspec/constraints/constraints.txt
+++ b/pyagentspec/constraints/constraints.txt
@@ -14,7 +14,7 @@ crewai==1.6.1
 
 # LangGraph adapter
 langgraph==1.2.0
-langchain==1.3.1
+langchain==1.3.9
 langchain-core==1.4.0
 langchain-openai==1.2.1
 langchain-ollama==1.0.1
diff --git a/pyagentspec/constraints/constraints_dev.txt b/pyagentspec/constraints/constraints_dev.txt
index 23ab31e4..cd063a4d 100644
--- a/pyagentspec/constraints/constraints_dev.txt
+++ b/pyagentspec/constraints/constraints_dev.txt
@@ -14,7 +14,7 @@ crewai==1.6.1
 
 # LangGraph adapter
 langgraph==1.2.0
-langchain==1.3.1
+langchain==1.3.9
 langchain-core==1.4.0
 langchain-openai==1.2.1
 langchain-ollama==1.0.1