diff --git a/pyproject.toml b/pyproject.toml
index 6043b41..3b32787 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -27,10 +27,10 @@ dependencies = []
 [project.optional-dependencies]
 openai   = ["openai~=1.30"]
 chroma   = ["chromadb~=0.4"]
-sentence = ["sentence-transformers~=2.6"]
+sentence = ["sentence-transformers>=2.6,<7.0"]
 serve    = ["fastapi~=0.110", "uvicorn~=0.27"]
 dev      = ["pytest~=8.0", "coverage~=7.0", "ruff~=0.5"]
-all      = ["openai~=1.30", "chromadb~=0.4", "sentence-transformers~=2.6", "fastapi~=0.110", "uvicorn~=0.27"]
+all      = ["openai~=1.30", "chromadb~=0.4", "sentence-transformers>=2.6,<7.0", "fastapi~=0.110", "uvicorn~=0.27"]
 
 [project.urls]
 Homepage       = "https://github.com/smartfind/loop-memory"