diff --git a/pwd.c b/pwd.c
index 81d0537..09d6474 100755
--- a/pwd.c
+++ b/pwd.c
@@ -6,19 +6,12 @@
 
 int main(int argc, char * argv[]) {
   int mode = 01; /* 01: print PWD -L, 02: print physical path -P */
+  char c;
 
-  if(argc > 1) {
-    for(int i = 1; i < argc; i++) {
-      if(argv[i][1] == 'L' && argv[i][2] == '\0') {
-	mode = 01;
-      }
-      else if(argv[i][1] == 'P' && argv[i][2] == '\0') {
-        mode = 02;
-      }
-      else {
-	fprintf(stderr, "%s: invalid option: %s\n", argv[0], argv[i]);
-	exit(1);
-      }
+  while((c = getopt(argc, argv, "LP")) != -1) {
+    switch(c) {
+      case 'L': mode = 01; break;
+      case 'P': mode = 02; break;
     }
   }