diff --git a/requirements.txt b/requirements.txt
index b5fe8f8..c8a0b11 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -2,6 +2,5 @@ numpy
 scipy
 matplotlib
 ambiance
-thermo
+thermo==0.1.40
 pypropep
-CoolProp
\ No newline at end of file
diff --git a/setup.py b/setup.py
index 7754279..66e3090 100644
--- a/setup.py
+++ b/setup.py
@@ -9,6 +9,6 @@
     name='bamboo',
     version='0.1',
     packages=find_packages(),
-    install_requires=['numpy', 'matplotlib', 'scipy', 'ambiance', 'thermo', 'pypropep', 'CoolProp'],
+    install_requires=['numpy', 'matplotlib', 'scipy', 'ambiance', 'thermo==0.1.40', 'pypropep'],
     description='1D isentropic nozzle flow for perfect gases',
 )