diff --git a/frontend/scanimage.c b/frontend/scanimage.c
index b5f147ffe..f716d8292 100644
--- a/frontend/scanimage.c
+++ b/frontend/scanimage.c
@@ -205,27 +205,28 @@ auth_callback (SANE_String_Const resource,
 		  if ((strlen (tmp) > 0) && (tmp[strlen (tmp) - 1] == '\r'))
 		    tmp[strlen (tmp) - 1] = 0;
 
-		  if (strchr (tmp, ':') != NULL)
+		  char *colon1 = strchr (tmp, ':');
+		  if (colon1 != NULL)
 		    {
-
-		      if (strchr (strchr (tmp, ':') + 1, ':') != NULL)
+		      char *colon2 = strchr (colon1 + 1, ':');
+		      if (colon2 != NULL)
 			{
 
-			  if ((strncmp (strchr (strchr (tmp, ':') + 1, ':') + 1, resource, len) == 0)
-			      && ((int) strlen (strchr (strchr (tmp, ':') + 1, ':') + 1) == len))
+			  if ((strncmp (colon2 + 1, resource, len) == 0)
+			      && ((int) strlen (colon2 + 1) == len))
 			    {
 
-			      if ((strchr (tmp, ':') - tmp) < SANE_MAX_USERNAME_LEN)
+			      if ((colon1 - tmp) < SANE_MAX_USERNAME_LEN)
 				{
 
-				  if ((strchr (strchr (tmp, ':') + 1, ':') - (strchr (tmp, ':') + 1)) < SANE_MAX_PASSWORD_LEN)
+				  if ((colon2 - (colon1 + 1)) < SANE_MAX_PASSWORD_LEN)
 				    {
 
-				      strncpy (username, tmp, strchr (tmp, ':') - tmp);
-				      username[strchr (tmp, ':') - tmp] = 0;
+				      strncpy (username, tmp, colon1 - tmp);
+				      username[colon1 - tmp] = 0;
 
-				      strncpy (password, strchr (tmp, ':') + 1, strchr (strchr (tmp, ':') + 1, ':') - (strchr (tmp, ':') + 1));
-				      password[strchr (strchr (tmp, ':') + 1, ':') - (strchr (tmp, ':') + 1)] = 0;
+				      strncpy (password, colon1 + 1, colon2 - (colon1 + 1));
+				      password[colon2 - (colon1 + 1)] = 0;
 
 				      query_user = 0;
 				      break;