diff --git a/cmake/external/openblas.cmake b/cmake/external/openblas.cmake
index e9180c4fc9bb43cd2070e5bc93c74c7a9ee6510a..b099831738599ef4aaedd444d0a5d3721bd1aba8 100644
--- a/cmake/external/openblas.cmake
+++ b/cmake/external/openblas.cmake
@@ -55,6 +55,7 @@ IF(NOT WIN32)
         INSTALL_COMMAND     make install NO_SHARED=1 NO_LAPACK=1 PREFIX=<INSTALL_DIR> 
         UPDATE_COMMAND      ""
         CONFIGURE_COMMAND   ""
+        BUILD_BYPRODUCTS    ${CBLAS_LIBRARIES}
     )
 ELSE(NOT WIN32)
     SET(CBLAS_LIBRARIES
@@ -83,6 +84,8 @@ ELSE(NOT WIN32)
         CMAKE_CACHE_ARGS    -DCMAKE_INSTALL_PREFIX:PATH=${CBLAS_INSTALL_DIR}
                             -DCMAKE_POSITION_INDEPENDENT_CODE:BOOL=ON
                             -DCMAKE_BUILD_TYPE:STRING=${THIRD_PARTY_BUILD_TYPE}
+        # ninja need to know where openblas.lib comes from
+        BUILD_BYPRODUCTS    ${CBLAS_LIBRARIES}
         )
     SET(OPENBLAS_SHARED_LIB  ${CBLAS_INSTALL_DIR}/bin/openblas${CMAKE_SHARED_LIBRARY_SUFFIX})
 ENDIF(NOT WIN32)