diff --git a/drivers/watchdog/wdrtas.c b/drivers/watchdog/wdrtas.c
index 5d3b1a8e28b0..a38fa4907c92 100644
--- a/drivers/watchdog/wdrtas.c
+++ b/drivers/watchdog/wdrtas.c
@@ -106,6 +106,8 @@ static int wdrtas_set_interval(int interval)
 	return result;
 }
 
+#define WDRTAS_SP_SPI_LEN 4
+
 /**
  * wdrtas_get_interval - returns the current watchdog interval
  * @fallback_value: value (in seconds) to use, if the RTAS call fails
@@ -119,10 +121,17 @@ static int wdrtas_set_interval(int interval)
 static int wdrtas_get_interval(int fallback_value)
 {
 	long result;
-	char value[4];
+	char value[WDRTAS_SP_SPI_LEN];
 
+	spin_lock(&rtas_data_buf_lock);
+	memset(rtas_data_buf, 0, WDRTAS_SP_SPI_LEN);
 	result = rtas_call(wdrtas_token_get_sp, 3, 1, NULL,
-			   WDRTAS_SP_SPI, (void *)__pa(&value), 4);
+			   WDRTAS_SP_SPI, __pa(rtas_data_buf),
+			   WDRTAS_SP_SPI_LEN);
+
+	memcpy(value, rtas_data_buf, WDRTAS_SP_SPI_LEN);
+	spin_unlock(&rtas_data_buf_lock);
+
 	if (value[0] != 0 || value[1] != 2 || value[3] != 0 || result < 0) {
 		printk(KERN_WARNING "wdrtas: could not get sp_spi watchdog "
 		       "timeout (%li). Continuing\n", result);