diff --git a/cmake/Modules/LAMMPSUtils.cmake b/cmake/Modules/LAMMPSUtils.cmake
index 9f624fc007..41e35a63a5 100644
--- a/cmake/Modules/LAMMPSUtils.cmake
+++ b/cmake/Modules/LAMMPSUtils.cmake
@@ -110,14 +110,15 @@ function(FetchPotentials pkgfolder potfolder)
       math(EXPR plusone "${blank}+1")
       string(SUBSTRING ${line} 0 ${blank} pot)
       string(SUBSTRING ${line} ${plusone} -1 sum)
-      if(EXISTS ${LAMMPS_POTENTIALS_DIR}/${pot})
+      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}")
+        message(STATUS "Downloading 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 ${LAMMPS_POTENTIALS_DIR})
+        file(REMOVE "${LAMMPS_POTENTIALS_DIR}/${pot}")
+        file(COPY "${CMAKE_BINARY_DIR}/${pot}" DESTINATION "${LAMMPS_POTENTIALS_DIR}")
       endif()
     endforeach()
   endif()