diff --git a/configure.ac b/configure.ac
index 1997587..cae618f 100644
--- a/configure.ac
+++ b/configure.ac
@@ -11,12 +11,14 @@ case "${host_os}" in
     linux*)
         AC_SUBST([MANPATH_CONF],  [/etc/manpath.config])
         AC_SUBST([REBUILD_MANDB], [mandb])
-        AC_SUBST([BASE64_FLAGS],  [-w0])
+        AC_SUBST([BASE64_ENCODE], [-w0])
+        AC_SUBST([BASE64_DECODE], [-d])
         ;;
     darwin*)
         AC_SUBST([MANPATH_CONF],  [/private/etc/man.conf])
         AC_SUBST([REBUILD_MANDB], [/usr/libexec/makewhatis])
-        AC_SUBST([BASE64_FLAGS],  [-b0])
+        AC_SUBST([BASE64_ENCODE], [-b0])
+        AC_SUBST([BASE64_DECODE], [-D])
         ;;
     *)
         AC_MSG_ERROR(["Unsupported OS: ${host_os}"])
diff --git a/src/Makefile.am b/src/Makefile.am
index 5496339..8efc76e 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -6,6 +6,7 @@ u6ac_SOURCES = logging.c lexer.c parser.c codegen.c u6ac.c
 u6a_SOURCES  = logging.c vm_stack.c vm_pool.c runtime.c u6a.c
 
 TEST_DIR = ${srcdir}/../tests
-DEJAGNU_GLOBALS = U6A_BIN=${srcdir}/u6a U6AC_BIN=${srcdir}/u6ac U6A_RUN=${TEST_DIR}/u6a_run B64_FLAGS=${BASE64_FLAGS}
-RUNTESTDEFAULTFLAGS = --srcdir=${TEST_DIR} --tool default ${DEJAGNU_GLOBALS}
+DEJAGNU_GLOBALS_BIN = U6A_BIN=${srcdir}/u6a U6AC_BIN=${srcdir}/u6ac U6A_RUN=${TEST_DIR}/u6a_run
+DEJAGNU_GLOBALS_BASE64 = B64_ENCODE=${BASE64_ENCODE} B64_DECODE=${BASE64_DECODE}
+RUNTESTDEFAULTFLAGS = --srcdir=${TEST_DIR} --tool default ${DEJAGNU_GLOBALS_BIN} ${DEJAGNU_GLOBALS_BASE64}
 EXTRA_DEJAGNU_SITE_CONFIG = ../tests/init.exp
diff --git a/tests/default/cat.exp b/tests/default/cat.exp
index 6e7bb05..c3d152b 100644
--- a/tests/default/cat.exp
+++ b/tests/default/cat.exp
@@ -19,11 +19,11 @@
 
 set tool "default"
 set timeout 1
-global B64_FLAGS
+global B64_ENCODE
 
 set rand_str_list { }
 for { set i 100 } { $i < 200 } { incr i } {
-    lappend rand_str_list [ exec head -c $i /dev/urandom | base64 $B64_FLAGS ]
+    lappend rand_str_list [ exec head -c $i /dev/urandom | base64 $B64_ENCODE ]
 }
 
 u6a_run "```s`d`@|i`ci" - - 1
diff --git a/tests/init.exp b/tests/init.exp
index d934d2c..77e6926 100644
--- a/tests/init.exp
+++ b/tests/init.exp
@@ -18,11 +18,10 @@
 ##
 
 proc u6a_run { src_code u6ac_opts u6a_opts has_input } {
-    global U6A_BIN U6AC_BIN U6A_RUN B64_FLAGS
+    global U6A_BIN U6AC_BIN U6A_RUN B64_ENCODE B64_DECODE
     set u6ac "$U6AC_BIN $u6ac_opts"
     set u6a "$U6A_BIN $u6a_opts"
-    set base64 "base64 $B64_FLAGS"
-    set run_cmd [ list $U6A_RUN $u6ac $u6a $base64 $src_code ]
+    set run_cmd [ list $U6A_RUN $u6ac $u6a $B64_ENCODE $B64_DECODE $src_code ]
     if $has_input {
         lappend run_cmd -
         set stty_init -echo
diff --git a/tests/u6a_run b/tests/u6a_run
index d85f7fe..471dee8 100755
--- a/tests/u6a_run
+++ b/tests/u6a_run
@@ -18,8 +18,8 @@
 ## along with this program.  If not, see <https://www.gnu.org/licenses/>.
 ##
 
-U6A_BYTECODE=`echo $4 | $1 - | $3`
+U6A_BYTECODE=`echo $5 | $1 - | base64 $3`
 test -z $U6A_BYTECODE && exit -1
-cat <(echo $U6A_BYTECODE | base64 -d) <(test $5 && cat $5) | $2 -
+cat <(echo $U6A_BYTECODE | base64 $4) <(test $6 && cat $6) | $2 -
 
-# Usage: ./u6a_run /path/to/u6ac/bin /path/to/u6a/bin /path/to/base64/bin source_code [input]
+# Usage: ./u6a_run u6ac_bin u6a_bin b64_encode_ops b64_decode_ops src_code [input_file]