diff --git a/m4/ax_cuda.m4 b/m4/ax_cuda.m4
index d69713384ff13cb24c13018bc1a2db0e366bf97c..3188f19c8e4770b6ed1f1cdbfc5c8110d8d98858 100644
--- a/m4/ax_cuda.m4
+++ b/m4/ax_cuda.m4
@@ -41,25 +41,28 @@ AC_DEFUN([AX_CUDA],
 AC_CHECK_PROG([NVCC_EXIST],[nvcc],["yes"],["no"])
 AS_IF([test "x$NVCC_EXIST" = "xno"],[],[
           NVCC=`which nvcc`
-          
+
           # Set CUDA_CFLAGS to $NVCC, where substring "bin/nvcc"
           # is substituted by "include".
-          CUDA_CFLAGS=" -I${NVCC%bin//nvcc}"
-          CUDA_CFLAGS=" -I${CUDA_CFLAGS%bin/nvcc}"
+          CUDA_CFLAGS=" ${NVCC%bin//nvcc}"
+          CUDA_CFLAGS=" ${CUDA_CFLAGS%bin/nvcc}"
           CUDA_CFLAGS=" -I${CUDA_CFLAGS}include"
 
           #Set CUDA_CFLAGS to $NVCC, where substring "bin/nvcc"
           #is substituted by "lib".
-          CUDA_LIBS=" -L${NVCC%bin//nvcc}"
-          CUDA_LIBS=" -L${CUDA_LIBS%bin/nvcc}"
+          CUDA_LIBS="${NVCC%bin//nvcc}"
+          CUDA_LIBS="${CUDA_LIBS%bin/nvcc}"
+          CUDA_PATH=$CUDA_LIBS
           CUDA_LIBS=" -L${CUDA_LIBS}lib"
 
           # If $build_cpu contains "_64", append "64" to CUDA_LIBS
           AS_IF([echo $build_cpu | grep -q "_64"],
                 [
-                 AS_IF([ test -d {CUDA_LIBS}lib64 ], [ CUDA_LIBS+="64" ])
-                 AS_IF([ ! command -v bumblebee >/dev/null  ], [ 
-                                                               CUDA_LIBS+=" -L/usr/lib64/nvidia-bumblebee/ "
+                 AS_IF([ test -d $CUDA_PATH/lib64 ], [ CUDA_LIBS+="64" ], [])
+                 # Be carefull the return code 0 mean true return code 1 mean false
+                 AS_IF([ command -v bumblebee >/dev/null ], [ CUDA_LIBS+=" -L/usr/lib64/nvidia-bumblebee/ "  ],
+                                                             [
+                                                               echo "bumblebee, NVIDIA optimus,  not found"
                                                              ])
                  AS_IF([ test -d /usr/local/cuda/lib64  ], [ CUDA_LIBS+=" -L/usr/local/cuda/lib64 "  ],
                        [
@@ -69,7 +72,7 @@ AS_IF([test "x$NVCC_EXIST" = "xno"],[],[
 
           # Append " -lcuda -lcudart" to CUDA_LIBS
           CUDA_LIBS+=" -lcuda -lcudart"
-
+          
           # Make variables available in Makefile.am
           AC_SUBST([CUDA_CFLAGS])
           AC_SUBST([CUDA_LIBS])