diff --git a/lib/com_err/lex.l b/lib/com_err/lex.l
index 921945cdf..f23ae5d7e 100644
--- a/lib/com_err/lex.l
+++ b/lib/com_err/lex.l
@@ -89,7 +89,7 @@ getstring(void)
     int i = 0;
     int c;
     int quote = 0;
-    while((c = input()) != EOF){
+    while(i < sizeof(x) - 1 && (c = input()) != EOF){
 	if(quote) {
 	    x[i++] = c;
 	    quote = 0;
@@ -110,6 +110,8 @@ getstring(void)
     }
     x[i] = '\0';
     yylval.string = strdup(x);
+    if (yylval.string)
+        err(1, "malloc");
     return STRING;
 }