diff --git a/devel-tools/build_test_library.cmake b/devel-tools/build_test_library.cmake
index e0b1484b8..eea8eb046 100644
--- a/devel-tools/build_test_library.cmake
+++ b/devel-tools/build_test_library.cmake
@@ -55,6 +55,12 @@ if(COLVARS_LEPTON)
   if(NOT DEFINED LEPTON_DIR)
     set(LEPTON_DIR "${COLVARS_SOURCE_DIR}/openmm-source/libraries/lepton")
     if(NOT EXISTS ${LEPTON_DIR})
+      # Try the parent folder
+      get_filename_component(LEPTON_DIR ${COLVARS_SOURCE_DIR} DIRECTORY)
+      set(LEPTON_DIR "${LEPTON_DIR}/openmm-source/libraries/lepton")
+    endif()
+    if(NOT EXISTS ${LEPTON_DIR})
+      # Giving up, cloning OpenMM
       execute_process(COMMAND git clone --depth=1 https://github.com/openmm/openmm.git "${COLVARS_SOURCE_DIR}/openmm-source")
     endif()
     message(STATUS "Using Lepton library from: ${LEPTON_DIR}")