diff --git a/src/interface/efi/efi_entropy.c b/src/interface/efi/efi_entropy.c
index 2a2fc9054..dca0b6f1d 100644
--- a/src/interface/efi/efi_entropy.c
+++ b/src/interface/efi/efi_entropy.c
@@ -179,6 +179,7 @@ static int efi_get_noise_ticks ( noise_sample_t *noise ) {
  * @ret rc		Return status code
  */
 static int efi_get_noise_rng ( noise_sample_t *noise ) {
+	static uint8_t prev[EFI_ENTROPY_RNG_LEN];
 	uint8_t buf[EFI_ENTROPY_RNG_LEN];
 	EFI_STATUS efirc;
 	int rc;
@@ -196,6 +197,17 @@ static int efi_get_noise_rng ( noise_sample_t *noise ) {
 		return rc;
 	}
 
+	/* Fail (and permanently disable the EFI RNG) if we get
+	 * consecutive identical results.
+	 */
+	if ( memcmp ( buf, prev, sizeof ( buf ) ) == 0 ) {
+		DBGC ( &tick, "ENTROPY detected broken EFI RNG:\n" );
+		DBGC_HDA ( &tick, 0, buf, sizeof ( buf ) );
+		efirng = NULL;
+		return -EIO;
+	}
+	memcpy ( prev, buf, sizeof ( prev ) );
+
 	/* Reduce random bytes to a single noise sample.  This seems
 	 * like overkill, but we have no way of knowing how much
 	 * entropy is actually present in the bytes returned by the