diff --git a/plugins/sudoers/getdate.c b/plugins/sudoers/getdate.c
index e97d91b1f..b48433512 100644
--- a/plugins/sudoers/getdate.c
+++ b/plugins/sudoers/getdate.c
@@ -1016,8 +1016,9 @@ static int yygrowstack()
     short *newss;
     YYSTYPE *newvs;
 
-    newsize = yystacksize ? yystacksize : YYINITSTACKSIZE;
-    if (newsize >= YYMAXDEPTH)
+    if ((newsize = yystacksize) == 0)
+        newsize = YYINITSTACKSIZE;
+    else if (newsize >= YYMAXDEPTH)
         return -1;
     else if ((newsize *= 2) > YYMAXDEPTH)
         newsize = YYMAXDEPTH;
@@ -1500,7 +1501,7 @@ case 41:
 	    yyval.Meridian = yyvsp[0].Meridian;
 	}
 break;
-#line 1451 "getdate.c"
+#line 1452 "getdate.c"
     }
     yyssp -= yym;
     yystate = *yyssp;
diff --git a/plugins/sudoers/gram.c b/plugins/sudoers/gram.c
index a953e2b24..02d5418ed 100644
--- a/plugins/sudoers/gram.c
+++ b/plugins/sudoers/gram.c
@@ -971,8 +971,9 @@ static int yygrowstack()
     short *newss;
     YYSTYPE *newvs;
 
-    newsize = yystacksize ? yystacksize : YYINITSTACKSIZE;
-    if (newsize >= YYMAXDEPTH)
+    if ((newsize = yystacksize) == 0)
+        newsize = YYINITSTACKSIZE;
+    else if (newsize >= YYMAXDEPTH)
         return -1;
     else if ((newsize *= 2) > YYMAXDEPTH)
         newsize = YYMAXDEPTH;
@@ -1849,7 +1850,7 @@ case 111:
 			    yyval.member = new_member(yyvsp[0].string, WORD);
 			}
 break;
-#line 1800 "gram.c"
+#line 1801 "gram.c"
     }
     yyssp -= yym;
     yystate = *yyssp;