diff --git a/cmake/Modules/LAMMPSUtils.cmake b/cmake/Modules/LAMMPSUtils.cmake
index c6b4933038..a87c0f567c 100644
--- a/cmake/Modules/LAMMPSUtils.cmake
+++ b/cmake/Modules/LAMMPSUtils.cmake
@@ -96,9 +96,15 @@ function(FetchPotentials pkgfolder potfolder)
       math(EXPR plusone "${blank}+1")
       string(SUBSTRING ${line} 0 ${blank} pot)
       string(SUBSTRING ${line} ${plusone} -1 sum)
-      message(STATUS "Checking external potential ${pot} from ${LAMMPS_POTENTIALS_URL}")
-      file(DOWNLOAD "${LAMMPS_POTENTIALS_URL}/${pot}.${sum}" "${LAMMPS_POTENTIALS_DIR}/${pot}"
-        EXPECTED_HASH MD5=${sum} SHOW_PROGRESS)
+      if(EXISTS ${LAMMPS_POTENTIALS_DIR}/${pot})
+        file(MD5 "${LAMMPS_POTENTIALS_DIR}/${pot}" oldsum)
+      endif()
+      if(NOT sum STREQUAL oldsum)
+        message(STATUS "Checking external potential ${pot} from ${LAMMPS_POTENTIALS_URL}")
+        file(DOWNLOAD "${LAMMPS_POTENTIALS_URL}/${pot}.${sum}" "${CMAKE_BINARY_DIR}/${pot}"
+          EXPECTED_HASH MD5=${sum} SHOW_PROGRESS)
+        file(COPY "${CMAKE_BINARY_DIR}/${pot}" DESTINATION ${LAMMPS_POTENTIALS_DIR})
+      endif()
     endforeach()
   endif()
 endfunction(FetchPotentials)