diff -ru parrot/config/gen/platform/win32/exec.c parrot-mod/config/gen/platform/win32/exec.c
--- parrot/config/gen/platform/win32/exec.c	2005-07-22 09:23:49.418830400 -0500
+++ parrot-mod/config/gen/platform/win32/exec.c	2005-07-22 12:35:17.030444800 -0500
@@ -63,22 +63,21 @@
     if (pmclen == 0) {
         internal_exception(NOSPAWN, "Empty argument array for spawnw");
     }
-    
+
     /* Now build command line. */
     for (i = 0; i < pmclen; i++) {
-    	   STRING *s = VTABLE_get_string_keyed_int(interpreter, cmdargs, i);
-           char *cs = string_to_cstring(interpreter, s);
-    	   if (cmdlinepos + s->strlen + 3 > cmdlinelen)
-           {
-    	       cmdlinelen += s->strlen + 4;
-               mem_sys_realloc(cmdline, cmdlinelen);
+        STRING *s = VTABLE_get_string_keyed_int(interpreter, cmdargs, i);
+        char *cs = string_to_cstring(interpreter, s);
+        if (cmdlinepos + s->strlen + 3 > cmdlinelen) {
+            cmdlinelen += s->strlen + 4;
+            cmdline = mem_sys_realloc(cmdline, cmdlinelen);
         }
         strcpy(cmdline + cmdlinepos, "\"");
         strcpy(cmdline + cmdlinepos + 1, cs);
         strcpy(cmdline + cmdlinepos + 1 + s->strlen, "\" ");
         cmdlinepos += s->strlen + 3;
     }
-    
+
     /* Start the child process. */
     memset(&si, 0, sizeof(si));
     si.cb = sizeof(si);
diff -ru parrot/t/op/spawnw.t parrot-mod/t/op/spawnw.t
--- parrot/t/op/spawnw.t	2005-07-19 08:34:56.005030400 -0500
+++ parrot-mod/t/op/spawnw.t	2005-07-22 12:53:26.052388600 -0500
@@ -34,7 +34,7 @@
 
 =cut
 
-use Parrot::Test tests => 6;
+use Parrot::Test tests => 7;
 
 # perl command coded this way to avoid platform 
 # quoting issue.
@@ -132,3 +132,31 @@
 CODE
 return code: 3
 OUTPUT
+
+pir_output_is(<<'CODE', <<'OUTPUT', "grow argv buffer");
+.sub test @MAIN
+        .local pmc args
+
+        $S0 = "exit length(qq{"
+        $I0 = 0
+loop:
+        if $I0 >= 1000 goto end
+        $S0 = concat $S0, "A"
+        inc $I0
+        branch loop
+end:
+        $S0 = concat $S0, "}) / 100"
+        new args, .PerlArray
+        push args, "perl"
+        push args, "-e"
+        push args, $S0
+        $I0 = spawnw args
+        shr $I1, $I0, 8
+        print   "return code: "
+        print   $I1
+        print   "\n"
+        end
+.end
+CODE
+return code: 10
+OUTPUT