diff --git a/src/brei-shared.c b/src/brei-shared.c
index a250a22..e9a3612 100644
--- a/src/brei-shared.c
+++ b/src/brei-shared.c
@@ -168,7 +168,7 @@ brei_demarshal(struct brei_context *brei, struct iobuf *buf, const char *signatu
 {
 	size_t nargs = strlen(signature);
 	if (nargs > 256) {
-		return brei_result_new(BREI_CONNECTION_DISCONNECT_REASON_ERROR,
+		return brei_result_new(BREI_CONNECTION_DISCONNECT_REASON_PROTOCOL,
 				       "Too many arguments in signature (%zu)", nargs);
 	}
 
@@ -202,7 +202,7 @@ brei_demarshal(struct brei_context *brei, struct iobuf *buf, const char *signatu
 
 			uint32_t slen32 = bytes_to_int32(slen);
 			if (end - p < slen32) {
-				return brei_result_new(BREI_CONNECTION_DISCONNECT_REASON_ERROR,
+				return brei_result_new(BREI_CONNECTION_DISCONNECT_REASON_PROTOCOL,
 						       "Invalid string length %zu, only %li bytes remaining", slen, (end - p) * 4);
 			}
 
@@ -210,7 +210,7 @@ brei_demarshal(struct brei_context *brei, struct iobuf *buf, const char *signatu
 
 			/* strings must be null-terminated */
 			if (slen && str[slen - 1] != '\0') {
-				return brei_result_new(BREI_CONNECTION_DISCONNECT_REASON_ERROR,
+				return brei_result_new(BREI_CONNECTION_DISCONNECT_REASON_PROTOCOL,
 						       "Message string not zero-terminated");
 			}
 
@@ -219,7 +219,7 @@ brei_demarshal(struct brei_context *brei, struct iobuf *buf, const char *signatu
 			break;
 			}
 		default:
-			return brei_result_new(BREI_CONNECTION_DISCONNECT_REASON_ERROR,
+			return brei_result_new(BREI_CONNECTION_DISCONNECT_REASON_PROTOCOL,
 					       "Invalid signature '%c'", *s);
 		}
 		arg++;
@@ -277,7 +277,7 @@ brei_marshal(struct brei_context *brei, struct iobuf *buf, const char *signature
 			break;
 		}
 		default:
-			return brei_result_new(BREI_CONNECTION_DISCONNECT_REASON_ERROR,
+			return brei_result_new(BREI_CONNECTION_DISCONNECT_REASON_PROTOCOL,
 					       "Invalid signature '%c'", *s);
 		}
 		s++;
@@ -470,7 +470,7 @@ MUNIT_TEST(test_brei_marshal_bad_sig)
 	_unref_(brei_result) *result = brei_demarshal(brei, buf, "nxoiusf", &nargs, &args);
 	munit_assert_ptr_not_null(result);
 	munit_assert_int(brei_result_get_reason(result), ==,
-			 BREI_CONNECTION_DISCONNECT_REASON_ERROR);
+			 BREI_CONNECTION_DISCONNECT_REASON_PROTOCOL);
 	munit_assert_int(nargs, ==, 789); /* nargs must not be touched on error */
 
 	return MUNIT_OK;