diff --git a/lib/libalpm/alpm.h b/lib/libalpm/alpm.h
index faba1330..1c8d232e 100644
--- a/lib/libalpm/alpm.h
+++ b/lib/libalpm/alpm.h
@@ -526,6 +526,9 @@ enum _pmerrno_t {
 	PM_ERR_PKG_INVALID_NAME,
 	PM_ERR_PKG_INVALID_ARCH,
 	PM_ERR_PKG_REPO_NOT_FOUND,
+	/* Signatures */
+	PM_ERR_SIG_INVALID,
+	PM_ERR_SIG_UNKNOWN,
 	/* Deltas */
 	PM_ERR_DLT_INVALID,
 	PM_ERR_DLT_PATCHFAILED,
diff --git a/lib/libalpm/error.c b/lib/libalpm/error.c
index dcf26074..71c058f6 100644
--- a/lib/libalpm/error.c
+++ b/lib/libalpm/error.c
@@ -115,6 +115,11 @@ const char SYMEXPORT *alpm_strerror(int err)
 			return _("package architecture is not valid");
 		case PM_ERR_PKG_REPO_NOT_FOUND:
 			return _("could not find repository for target");
+		/* Signatures */
+		case PM_ERR_SIG_INVALID:
+			return _("invalid PGP signature");
+		case PM_ERR_SIG_UNKNOWN:
+			return _("unknown PGP signature");
 		/* Deltas */
 		case PM_ERR_DLT_INVALID:
 			return _("invalid or corrupted delta");