diff --git a/src/Parsers/ASTAlterQuery.cpp b/src/Parsers/ASTAlterQuery.cpp
index f323f66be17..1309037ec01 100644
--- a/src/Parsers/ASTAlterQuery.cpp
+++ b/src/Parsers/ASTAlterQuery.cpp
@@ -146,7 +146,7 @@ void ASTAlterCommand::formatImpl(
     }
     else if (type == ASTAlterCommand::ADD_CONSTRAINT)
     {
-        settings.ostr << (settings.hilite ? hilite_keyword : "") << indent_str << "ADD CONSTRAINT" << (if_not_exists ? "IF NOT EXISTS " : "") << (settings.hilite ? hilite_none : "");
+        settings.ostr << (settings.hilite ? hilite_keyword : "") << indent_str << "ADD CONSTRAINT " << (if_not_exists ? "IF NOT EXISTS " : "") << (settings.hilite ? hilite_none : "");
         constraint_decl->formatImpl(settings, state, frame);
     }
     else if (type == ASTAlterCommand::DROP_CONSTRAINT)
diff --git a/tests/queries/0_stateless/01318_alter_add_constraint_format.reference b/tests/queries/0_stateless/01318_alter_add_constraint_format.reference
new file mode 100644
index 00000000000..4283da7b3af
--- /dev/null
+++ b/tests/queries/0_stateless/01318_alter_add_constraint_format.reference
@@ -0,0 +1 @@
+ALTER TABLE replicated_constraints1 ADD CONSTRAINT IF NOT EXISTS b_constraint CHECK b > 10 
diff --git a/tests/queries/0_stateless/01318_alter_add_constraint_format.sh b/tests/queries/0_stateless/01318_alter_add_constraint_format.sh
new file mode 100755
index 00000000000..f8eb655a766
--- /dev/null
+++ b/tests/queries/0_stateless/01318_alter_add_constraint_format.sh
@@ -0,0 +1,8 @@
+#!/usr/bin/env bash
+
+CURDIR=$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)
+. $CURDIR/../shell_config.sh
+
+set -e
+
+$CLICKHOUSE_FORMAT --oneline <<<"ALTER TABLE replicated_constraints1 ADD CONSTRAINT IF NOT EXISTS b_constraint CHECK b > 10"