diff --git a/CMakeLists.txt b/CMakeLists.txt
index 07df064d23..9bf3696f97 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -399,8 +399,8 @@ if (BLAS++)
   include(ExternalProject)
   ExternalProject_Add(blaspp
 	  URL https://bitbucket.org/icl/blaspp/downloads/blaspp-2020.10.02.tar.gz
-	  CONFIGURE_COMMAND ${CMAKE_COMMAND} -E env LIBRARY_PATH=${CMAKE_BINARY_DIR}/lib LD_LIBRARY_PATH=${PROJECT_BINARY_DIR}/lib ${CMAKE_COMMAND} -DCMAKE_INSTALL_PREFIX=${PROJECT_BINARY_DIR} -DCMAKE_INSTALL_LIBDIR=lib -DBUILD_SHARED_LIBS=${BUILD_SHARED_LIBS} ${PROJECT_BINARY_DIR}/blaspp-prefix/src/blaspp
-	  BUILD_COMMAND ${CMAKE_COMMAND} -E env LIBRARY_PATH=${PROJECT_BINARY_DIR}/lib LIB_SUFFIX="" make
+	  CONFIGURE_COMMAND ${CMAKE_COMMAND} -E env LIBRARY_PATH=$ENV{LIBRARY_PATH}:${CMAKE_BINARY_DIR}/lib LD_LIBRARY_PATH=$ENV{LD_LIBRARY_PATH}:${PROJECT_BINARY_DIR}/lib ${CMAKE_COMMAND} -DCMAKE_INSTALL_PREFIX=${PROJECT_BINARY_DIR} -DCMAKE_INSTALL_LIBDIR=lib -DBUILD_SHARED_LIBS=${BUILD_SHARED_LIBS} ${PROJECT_BINARY_DIR}/blaspp-prefix/src/blaspp
+	  BUILD_COMMAND ${CMAKE_COMMAND} -E env LIBRARY_PATH=$ENV{LIBRARY_PATH}:${PROJECT_BINARY_DIR}/lib LIB_SUFFIX="" make
 	  INSTALL_COMMAND make PREFIX=${PROJECT_BINARY_DIR} LIB_SUFFIX="" install
 	  )
   ExternalProject_Add_StepDependencies(blaspp build ${BLAS_LIBRARIES})
@@ -412,16 +412,16 @@ if (LAPACK++)
   if (BUILD_SHARED_LIBS)
   ExternalProject_Add(lapackpp
 	  URL https://bitbucket.org/icl/lapackpp/downloads/lapackpp-2020.10.02.tar.gz
-	  CONFIGURE_COMMAND ${CMAKE_COMMAND} -E env LIBRARY_PATH=${CMAKE_BINARY_DIR}/lib LD_LIBRARY_PATH=${PROJECT_BINARY_DIR}/lib ${CMAKE_COMMAND} -DCMAKE_INSTALL_PREFIX=${PROJECT_BINARY_DIR} -DCMAKE_INSTALL_LIBDIR=lib -DLAPACK_LIBRARIES=${LAPACK_LIBRARIES} -DBUILD_SHARED_LIBS=${BUILD_SHARED_LIBS}  ${PROJECT_BINARY_DIR}/lapackpp-prefix/src/lapackpp
-	  BUILD_COMMAND ${CMAKE_COMMAND} -E env LIBRARY_PATH=${PROJECT_BINARY_DIR}/lib LIB_SUFFIX="" make
+	  CONFIGURE_COMMAND ${CMAKE_COMMAND} -E env LIBRARY_PATH=$ENV{LIBRARY_PATH}:${CMAKE_BINARY_DIR}/lib LD_LIBRARY_PATH=$ENV{LD_LIBRARY_PATH}:${PROJECT_BINARY_DIR}/lib ${CMAKE_COMMAND} -DCMAKE_INSTALL_PREFIX=${PROJECT_BINARY_DIR} -DCMAKE_INSTALL_LIBDIR=lib -DLAPACK_LIBRARIES=${LAPACK_LIBRARIES} -DBUILD_SHARED_LIBS=${BUILD_SHARED_LIBS}  ${PROJECT_BINARY_DIR}/lapackpp-prefix/src/lapackpp
+	  BUILD_COMMAND ${CMAKE_COMMAND} -E env LIBRARY_PATH=$ENV{LIBRARY_PATH}:${PROJECT_BINARY_DIR}/lib LIB_SUFFIX="" make
 	  INSTALL_COMMAND make PREFIX=${PROJECT_BINARY_DIR} LIB_SUFFIX="" install
 	  )
   else ()
 # FIXME this does not really work as the libraries list gets converted to a semicolon-separated list somewhere in the lapack++ build files
   ExternalProject_Add(lapackpp
 	  URL https://bitbucket.org/icl/lapackpp/downloads/lapackpp-2020.10.02.tar.gz
-	  CONFIGURE_COMMAND env LIBRARY_PATH=${CMAKE_BINARY_DIR}/lib LD_LIBRARY_PATH=${PROJECT_BINARY_DIR}/lib ${CMAKE_COMMAND} -DCMAKE_INSTALL_PREFIX=${PROJECT_BINARY_DIR} -DCMAKE_INSTALL_LIBDIR=lib -DLAPACK_LIBRARIES="${PROJECT_BINARY_DIR}/lib/liblapack.a -lgfortran"  -DBUILD_SHARED_LIBS=${BUILD_SHARED_LIBS}  ${PROJECT_BINARY_DIR}/lapackpp-prefix/src/lapackpp
-	  BUILD_COMMAND env LIBRARY_PATH=${PROJECT_BINARY_DIR}/lib LIB_SUFFIX="" make
+	  CONFIGURE_COMMAND env LIBRARY_PATH=$ENV{LIBRARY_PATH}:${CMAKE_BINARY_DIR}/lib LD_LIBRARY_PATH=$ENV{LD_LIBRARY_PATH}:${PROJECT_BINARY_DIR}/lib ${CMAKE_COMMAND} -DCMAKE_INSTALL_PREFIX=${PROJECT_BINARY_DIR} -DCMAKE_INSTALL_LIBDIR=lib -DLAPACK_LIBRARIES="${PROJECT_BINARY_DIR}/lib/liblapack.a -lgfortran"  -DBUILD_SHARED_LIBS=${BUILD_SHARED_LIBS}  ${PROJECT_BINARY_DIR}/lapackpp-prefix/src/lapackpp
+	  BUILD_COMMAND env LIBRARY_PATH=$ENV{LIBRARY_PATH}:${PROJECT_BINARY_DIR}/lib LIB_SUFFIX="" make
 	  INSTALL_COMMAND make PREFIX=${PROJECT_BINARY_DIR} LIB_SUFFIX="" install
   )
   endif()