diff --git a/pyproject.toml b/pyproject.toml
index 880a5c7..7ebde26 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -31,7 +31,7 @@ requires = [
     "aiohttp>=3.12.14",
     "bcrypt",
     "portalocker>=2.8",
-    "nostr-sdk>=0.42.1",
+    "nostr-sdk>=0.42.1,<0.43",
     "websocket-client==1.7.0",
     "websockets>=15.0.0",
     "tomli",
diff --git a/src/requirements.txt b/src/requirements.txt
index 4008154..ac9a950 100644
--- a/src/requirements.txt
+++ b/src/requirements.txt
@@ -11,7 +11,7 @@ pytest>=7.0
 pytest-cov
 pytest-xdist
 portalocker>=2.8
-nostr-sdk>=0.42.1
+nostr-sdk>=0.42.1,<0.43
 websocket-client==1.7.0
 
 websockets>=15.0.0
diff --git a/src/runtime_requirements.txt b/src/runtime_requirements.txt
index 1bde15f..f1b13ec 100644
--- a/src/runtime_requirements.txt
+++ b/src/runtime_requirements.txt
@@ -10,7 +10,7 @@ mnemonic
 aiohttp>=3.12.14
 bcrypt
 portalocker>=2.8
-nostr-sdk>=0.42.1
+nostr-sdk>=0.42.1,<0.43
 websocket-client==1.7.0
 
 websockets>=15.0.0