--- /dev/null	2014-11-04 11:17:12.000000000 -0600
+++ ./files/patch-pam_google_authenticator.c	2014-11-04 11:07:37.000000000 -0600
@@ -0,0 +1,67 @@
+--- pam_google_authenticator.c.orig	2014-01-30 15:17:38.000000000 +0000
++++ pam_google_authenticator.c	2014-11-04 17:05:55.000000000 +0000
+@@ -503,10 +503,6 @@
+ }
+ #endif
+ 
+-static int get_timestamp(void) {
+-  return get_time()/30;
+-}
+-
+ static int comparator(const void *a, const void *b) {
+   return *(unsigned int *)a - *(unsigned int *)b;
+ }
+@@ -538,6 +534,41 @@
+   return NULL;
+ }
+ 
++#if !defined(STEPSIZE)
++static int get_timestamp(void) {
++  return get_time()/30;
++}
++#else
++static int get_timestamp(pam_handle_t *pamh, const char *secret_filename,
++                       const char *buf) {
++  const char *value = get_cfg_value(pamh, "STEP_SIZE", buf);
++  if (!value) {
++    // Default step size is 30.
++    free((void *)value);
++    return get_time()/30;
++  } else if (value == &oom) {
++    // Out of memory. This is a fatal error.
++    return 0;
++  }
++
++  char *endptr;
++  errno = 0;
++  int step = (int)strtoul(value, &endptr, 10);
++  if (errno || !*value || value == endptr ||
++      (*endptr && *endptr != ' ' && *endptr != '\t' &&
++       *endptr != '\n' && *endptr != '\r') ||
++      step < 1 || step > 60) {
++    free((void *)value);
++    log_message(LOG_ERR, pamh, "Invalid STEP_SIZE option in \"%s\"",
++                secret_filename);
++    return 0;
++  }
++  free((void *)value);
++
++  return get_time()/step;
++}
++#endif
++
+ static int set_cfg_value(pam_handle_t *pamh, const char *key, const char *val,
+                          char **buf) {
+   size_t key_len = strlen(key);
+@@ -1162,7 +1193,11 @@
+   }
+ 
+   // Compute verification codes and compare them with user input
++#if !defined(STEPSIZE)
+   const int tm = get_timestamp();
++#else
++  const int tm = get_timestamp(pamh, secret_filename, *buf);
++#endif
+   const char *skew_str = get_cfg_value(pamh, "TIME_SKEW", *buf);
+   if (skew_str == &oom) {
+     // Out of memory. This is a fatal error