diff --git a/drivers/char/tpm/tpm-interface.c b/drivers/char/tpm/tpm-interface.c
index 6e368ee7bbec..bd2128e0b56c 100644
--- a/drivers/char/tpm/tpm-interface.c
+++ b/drivers/char/tpm/tpm-interface.c
@@ -767,7 +767,7 @@ EXPORT_SYMBOL_GPL(tpm_pcr_read);
 
 #define TPM_ORD_PCR_EXTEND cpu_to_be32(20)
 #define EXTEND_PCR_RESULT_SIZE 34
-#define EXTEND_PCR_RESULT_BODY_SIZE 24
+#define EXTEND_PCR_RESULT_BODY_SIZE 20
 static const struct tpm_input_header pcrextend_header = {
 	.tag = TPM_TAG_RQU_COMMAND,
 	.length = cpu_to_be32(34),