diff --git a/tools/test/perform/pio_standalone.c b/tools/test/perform/pio_standalone.c
index db8633e3a5f..ded15a425fd 100644
--- a/tools/test/perform/pio_standalone.c
+++ b/tools/test/perform/pio_standalone.c
@@ -26,11 +26,6 @@ MPI_Info h5_io_info_g = MPI_INFO_NULL; /* MPI INFO object for IO */
 /* global variables */
 int nCols = 80;
 
-/* ``get_option'' variables */
-int         H5_opterr = 1; /*get_option prints errors if this is on */
-int         H5_optind = 1; /*token pointer                          */
-const char *H5_optarg;     /*flag argument (or value)               */
-
 int
 get_option(int argc, const char **argv, const char *opts, const struct h5_long_options *l_opts)
 {
diff --git a/tools/test/perform/pio_standalone.h b/tools/test/perform/pio_standalone.h
index 4b5c7b2d145..ef6d97b4b90 100644
--- a/tools/test/perform/pio_standalone.h
+++ b/tools/test/perform/pio_standalone.h
@@ -454,9 +454,9 @@ void h5_dump_info_object(MPI_Info info);
 
 /** From h5tools_utils.h **/
 
-extern int         H5_opterr; /* getoption prints errors if this is on    */
-extern int         H5_optind; /* token pointer                            */
-extern const char *H5_optarg; /* flag argument (or value)                 */
+H5_DLLVAR int         H5_opterr; /* getoption prints errors if this is on    */
+H5_DLLVAR int         H5_optind; /* token pointer                            */
+H5_DLLVAR const char *H5_optarg; /* flag argument (or value)                 */
 
 enum h5_arg_level {
     no_arg = 0,  /* doesn't take an argument     */
diff --git a/tools/test/perform/sio_standalone.c b/tools/test/perform/sio_standalone.c
index 2e793fbc365..7c22b5328d1 100644
--- a/tools/test/perform/sio_standalone.c
+++ b/tools/test/perform/sio_standalone.c
@@ -22,11 +22,6 @@
 /* global variables */
 int nCols = 80;
 
-/* ``get_option'' variables */
-int         H5_opterr = 1; /*get_option prints errors if this is on */
-int         H5_optind = 1; /*token pointer                          */
-const char *H5_optarg;     /*flag argument (or value)               */
-
 int
 get_option(int argc, const char **argv, const char *opts, const struct h5_long_options *l_opts)
 {
diff --git a/tools/test/perform/sio_standalone.h b/tools/test/perform/sio_standalone.h
index 098b98a1474..3b699dc5955 100644
--- a/tools/test/perform/sio_standalone.h
+++ b/tools/test/perform/sio_standalone.h
@@ -469,9 +469,9 @@ void h5_dump_info_object(MPI_Info info);
 
 /** From h5tools_utils.h **/
 
-extern int         H5_opterr; /* getoption prints errors if this is on    */
-extern int         H5_optind; /* token pointer                            */
-extern const char *H5_optarg; /* flag argument (or value)                 */
+H5_DLLVAR int         H5_opterr; /* getoption prints errors if this is on    */
+H5_DLLVAR int         H5_optind; /* token pointer                            */
+H5_DLLVAR const char *H5_optarg; /* flag argument (or value)                 */
 
 enum h5_arg_level {
     no_arg = 0,  /* doesn't take an argument     */