diff --git a/parser/sql/dialect/firebird/src/main/antlr4/imports/firebird/BaseRule.g4 b/parser/sql/dialect/firebird/src/main/antlr4/imports/firebird/BaseRule.g4
index 26179efc0ee22..2474c05c47a10 100644
--- a/parser/sql/dialect/firebird/src/main/antlr4/imports/firebird/BaseRule.g4
+++ b/parser/sql/dialect/firebird/src/main/antlr4/imports/firebird/BaseRule.g4
@@ -112,10 +112,6 @@ tableName
     : (owner DOT_)? name
     ;
 
-packageName
-    : identifier
-    ;
-
 parameterName
     : identifier
     ;
@@ -254,6 +250,7 @@ predicate
     | bitExpr NOT? STARTING WITH? bitExpr
     | bitExpr IS NOT? DISTINCT FROM bitExpr
     | bitExpr IS NOT? NULL
+    | bitExpr NOT? SIMILAR TO bitExpr (ESCAPE bitExpr)?
     | bitExpr
     ;
 
diff --git a/parser/sql/dialect/firebird/src/main/antlr4/imports/firebird/DDLStatement.g4 b/parser/sql/dialect/firebird/src/main/antlr4/imports/firebird/DDLStatement.g4
index 71c718b7d3721..82560bf10bca5 100644
--- a/parser/sql/dialect/firebird/src/main/antlr4/imports/firebird/DDLStatement.g4
+++ b/parser/sql/dialect/firebird/src/main/antlr4/imports/firebird/DDLStatement.g4
@@ -262,7 +262,7 @@ dataTypeOption
     ;
 
 checkConstraintDefinition
-    : (CONSTRAINT ignoredIdentifier?)? CHECK expr
+    : (CONSTRAINT ignoredIdentifier?)? checkClause
     ;
 
 referenceDefinition
diff --git a/parser/sql/dialect/firebird/src/main/antlr4/imports/firebird/FirebirdKeyword.g4 b/parser/sql/dialect/firebird/src/main/antlr4/imports/firebird/FirebirdKeyword.g4
index 05a9ab9bb6b98..e3acb2fa83d2b 100644
--- a/parser/sql/dialect/firebird/src/main/antlr4/imports/firebird/FirebirdKeyword.g4
+++ b/parser/sql/dialect/firebird/src/main/antlr4/imports/firebird/FirebirdKeyword.g4
@@ -973,4 +973,8 @@ DATABASE
 
 COMMENT
     : C O M M E N T
+    ;
+
+SIMILAR
+    : S I M I L A R
     ;
\ No newline at end of file