diff --git a/docs/pages/release_notes.md b/docs/pages/release_notes.md
index 2826a1432b..24f0987147 100644
--- a/docs/pages/release_notes.md
+++ b/docs/pages/release_notes.md
@@ -50,6 +50,7 @@ This is a {{ site.pmd.release_type }} release.
   * [#5086](https://github.com/pmd/pmd/pull/5086): \[plsql] Fixed issue with missing optional table alias in MERGE usage
   * [#5087](https://github.com/pmd/pmd/pull/5087): \[plsql] Add support for SQL_MACRO
   * [#5088](https://github.com/pmd/pmd/pull/5088): \[plsql] Add support for 'DEFAULT' clause on the arguments of some oracle functions
+  * [#5133](https://github.com/pmd/pmd/issues/5133): \[plsql] AssertionError: Root of the tree should implement RootNode for a PL/SQL type declaration
 * cli
   * [#5120](https://github.com/pmd/pmd/issues/5120): \[cli] Can't start designer under Windows
 * core
diff --git a/pmd-plsql/etc/grammar/PLSQL.jjt b/pmd-plsql/etc/grammar/PLSQL.jjt
index c5d970e242..787470b79e 100644
--- a/pmd-plsql/etc/grammar/PLSQL.jjt
+++ b/pmd-plsql/etc/grammar/PLSQL.jjt
@@ -993,12 +993,8 @@ ASTScalarDataTypeName ScalarDataTypeName() :
     LOOKAHEAD(4) (<WITH><LOCAL><TIME><ZONE> {name.append(" WITH LOCAL TIME ZONE");}) |
     LOOKAHEAD(3) (<WITH><TIME><ZONE> {name.append( " WITH TIME ZONE");}) |
     LOOKAHEAD(2) (<TO><MONTH> {name.append( " TO MONTH");}) |
-    LOOKAHEAD(2) (<TO><SECOND> {name.append( " TO SECOND");}
-			(
-			  LOOKAHEAD(2) "(" precision=NumericLiteral() {name.append( "(" + precision) ;}
-					")" {name.append( ")");}
-			)?
-                 )
+    LOOKAHEAD(2) <TO><SECOND> { name.append(" TO SECOND"); }
+                [ LOOKAHEAD(2) "(" precision = NumericLiteral() { name.append("(").append(precision.getImage()).append(")"); } ")" ]
    ]
 
       { jjtThis.setImage(name.toString()) ;  return jjtThis; }
diff --git a/pmd-plsql/src/test/java/net/sourceforge/pmd/lang/plsql/ast/PlsqlTreeDumpTest.java b/pmd-plsql/src/test/java/net/sourceforge/pmd/lang/plsql/ast/PlsqlTreeDumpTest.java
index 3594733782..78c4dbd4fe 100644
--- a/pmd-plsql/src/test/java/net/sourceforge/pmd/lang/plsql/ast/PlsqlTreeDumpTest.java
+++ b/pmd-plsql/src/test/java/net/sourceforge/pmd/lang/plsql/ast/PlsqlTreeDumpTest.java
@@ -71,4 +71,9 @@ class PlsqlTreeDumpTest extends BaseTreeDumpTest {
     void parseSelectExpression() {
         doTest("SelectExpressions");
     }
+
+    @Test
+    void issue5133SubTypeDefinition() {
+        doTest("Issue5133SubTypeDefinition");
+    }
 }
diff --git a/pmd-plsql/src/test/resources/net/sourceforge/pmd/lang/plsql/ast/Issue5133SubTypeDefinition.pls b/pmd-plsql/src/test/resources/net/sourceforge/pmd/lang/plsql/ast/Issue5133SubTypeDefinition.pls
new file mode 100644
index 0000000000..d3745f00c0
--- /dev/null
+++ b/pmd-plsql/src/test/resources/net/sourceforge/pmd/lang/plsql/ast/Issue5133SubTypeDefinition.pls
@@ -0,0 +1,8 @@
+--
+-- from https://github.com/pmd/pmd/issues/5133
+--
+
+CREATE or REPLACE PACKAGE x as
+    type last_run_duration is interval day(9) to second(6);
+end x;
+/
diff --git a/pmd-plsql/src/test/resources/net/sourceforge/pmd/lang/plsql/ast/Issue5133SubTypeDefinition.txt b/pmd-plsql/src/test/resources/net/sourceforge/pmd/lang/plsql/ast/Issue5133SubTypeDefinition.txt
new file mode 100644
index 0000000000..e60436b8c4
--- /dev/null
+++ b/pmd-plsql/src/test/resources/net/sourceforge/pmd/lang/plsql/ast/Issue5133SubTypeDefinition.txt
@@ -0,0 +1,13 @@
++- Input[@CanonicalImage = null, @ExcludedLinesCount = 0, @ExcludedRangesCount = 0]
+   +- PackageSpecification[@CanonicalImage = "X", @Image = "x", @ObjectName = "x"]
+      +- ObjectNameDeclaration[@CanonicalImage = "X", @Image = "x"]
+      |  +- ID[@CanonicalImage = "X", @Image = "x"]
+      +- DeclarativeSection[@CanonicalImage = null]
+      |  +- DeclarativeUnit[@CanonicalImage = null]
+      |     +- SubTypeDefinition[@CanonicalImage = "LAST_RUN_DURATION", @Image = "last_run_duration"]
+      |        +- QualifiedID[@CanonicalImage = "LAST_RUN_DURATION", @Image = "last_run_duration"]
+      |        +- Datatype[@CanonicalImage = "INTERVAL DAY(9) TO SECOND(6)", @Image = "INTERVAL DAY(9) TO SECOND(6)", @TypeImage = "INTERVAL DAY(9) TO SECOND(6)"]
+      |           +- ScalarDataTypeName[@CanonicalImage = "INTERVAL DAY(9) TO SECOND(6)", @Image = "INTERVAL DAY(9) TO SECOND(6)"]
+      |              +- NumericLiteral[@CanonicalImage = "9", @Image = "9"]
+      |              +- NumericLiteral[@CanonicalImage = "6", @Image = "6"]
+      +- ID[@CanonicalImage = "X", @Image = "x"]