diff --git a/ALTAIR/altair_sys.c b/ALTAIR/altair_sys.c
index 83093ba0..f3b2d471 100644
--- a/ALTAIR/altair_sys.c
+++ b/ALTAIR/altair_sys.c
@@ -234,6 +234,7 @@ t_stat parse_sym (CONST char *cptr, t_addr addr, UNIT *uptr, t_value *val, int32
 int32 cflag, i = 0, j, r;
 char gbuf[CBUFSIZE];
 
+memset (gbuf, 0, sizeof (gbuf));
 cflag = (uptr == NULL) || (uptr == &cpu_unit);
 while (isspace (*cptr)) cptr++;                         /* absorb spaces */
 if ((sw & SWMASK ('A')) || ((*cptr == '\'') && cptr++)) { /* ASCII char? */
@@ -251,7 +252,7 @@ if ((sw & SWMASK ('C')) || ((*cptr == '"') && cptr++)) { /* ASCII string? */
    or numeric (including spaces).
 */
 
-while (1) {
+while (i < sizeof (gbuf)) {
     if (*cptr == ',' || *cptr == '\0' ||
          isdigit(*cptr))
             break;
@@ -285,9 +286,7 @@ if (toupper(gbuf[0]) == 'M' &&
 
 /* kill trailing spaces if any */
 gbuf[i] = '\0';
-for (j = i - 1; gbuf[j] == ' '; j--) {
-    gbuf[j] = '\0';
-}
+sim_trim_endspc (gbuf);
 
 /* find opcode in table */
 for (j = 0; j < 256; j++) {