diff --git a/security/keymint/aidl/android/hardware/security/keymint/KeyParameterValue.aidl b/security/keymint/aidl/android/hardware/security/keymint/KeyParameterValue.aidl
index 59016f2c3b..924f4023ba 100644
--- a/security/keymint/aidl/android/hardware/security/keymint/KeyParameterValue.aidl
+++ b/security/keymint/aidl/android/hardware/security/keymint/KeyParameterValue.aidl
@@ -48,7 +48,7 @@ union KeyParameterValue {
     boolean boolValue; // Always true, if present.
     int integer;
     long longInteger;
-    long dateTime;
+    long dateTime; // In milliseconds from epoch
 
     byte[] blob;
 }
diff --git a/security/keymint/aidl/android/hardware/security/keymint/Tag.aidl b/security/keymint/aidl/android/hardware/security/keymint/Tag.aidl
index 8fbc91a0ef..66f79ce041 100644
--- a/security/keymint/aidl/android/hardware/security/keymint/Tag.aidl
+++ b/security/keymint/aidl/android/hardware/security/keymint/Tag.aidl
@@ -935,15 +935,15 @@ enum Tag {
 
     /**
      * Tag::CERTIFICATE_NOT_BEFORE the beginning of the validity of the certificate in UNIX epoch
-     * time in seconds.  This value is used when generating attestation or self signed certificates.
-     * ErrorCode::MISSING_NOT_BEFORE must be returned if this tag is not provided if this tag is not
-     * provided to generateKey or importKey.
+     * time in milliseconds.  This value is used when generating attestation or self signed
+     * certificates.  ErrorCode::MISSING_NOT_BEFORE must be returned if this tag is not provided if
+     * this tag is not provided to generateKey or importKey.
      */
     CERTIFICATE_NOT_BEFORE = (6 << 28) /* TagType:DATE */ | 1008,
 
     /**
      * Tag::CERTIFICATE_NOT_AFTER the end of the validity of the certificate in UNIX epoch time in
-     * seconds.  This value is used when generating attestation or self signed certificates.
+     * milliseconds.  This value is used when generating attestation or self signed certificates.
      * ErrorCode::MISSING_NOT_AFTER must be returned if this tag is not provided to generateKey or
      * importKey.
      */