diff --git a/CMakeLists.txt b/CMakeLists.txt
index 546c9650392a2efee8b8209293719a7f4581b1e3..6b0cd5ce9587fc7fc40ec58d40b2ad68155077b7 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -86,7 +86,7 @@ if(NOT DISABLE_DOCUMENTATION)
   # set this to the URL corresponding to the version of OST you are using
   set(OST_DOC_URL "https://www.openstructure.org/docs/dev")
 endif()
-find_package(OPENSTRUCTURE 1.9 REQUIRED 
+find_package(OPENSTRUCTURE 1.8 REQUIRED
              COMPONENTS io mol seq seq_alg mol_alg conop img mol_mm)
 
 if(CMAKE_COMPILER_IS_GNUCXX)