diff --git a/powershell/ql/lib/semmle/code/powershell/dataflow/internal/DataFlowPrivate.qll b/powershell/ql/lib/semmle/code/powershell/dataflow/internal/DataFlowPrivate.qll
index 20bbe7f6b1f..bd0aa428094 100644
--- a/powershell/ql/lib/semmle/code/powershell/dataflow/internal/DataFlowPrivate.qll
+++ b/powershell/ql/lib/semmle/code/powershell/dataflow/internal/DataFlowPrivate.qll
@@ -47,15 +47,6 @@ private class ExprNodeImpl extends ExprNode, NodeImpl {
   override string toStringImpl() { result = this.getExprNode().toString() }
 }
 
-/** Gets the SSA definition node corresponding to parameter `p`. */
-pragma[nomagic]
-SsaImpl::DefinitionExt getParameterDef(Parameter p) {
-  exists(EntryBasicBlock bb, int i |
-    bb.getNode(i).getAstNode() = p and
-    result.definesAt(_, bb, i, _)
-  )
-}
-
 /** Provides logic related to SSA. */
 module SsaFlow {
   private module Impl = SsaImpl::DataFlowIntegration;
@@ -453,7 +444,7 @@ class SsaDefinitionNodeImpl extends SsaNode {
     exists(SsaImpl::Definition def | def = this.getDefinition() |
       not def instanceof Ssa::WriteDefinition
       or
-      def = getParameterDef(_)
+      def = SsaImpl::getParameterDef(_)
     )
   }
 }
diff --git a/powershell/ql/lib/semmle/code/powershell/dataflow/internal/SsaImpl.qll b/powershell/ql/lib/semmle/code/powershell/dataflow/internal/SsaImpl.qll
index 33741d01863..037f58e8eb7 100644
--- a/powershell/ql/lib/semmle/code/powershell/dataflow/internal/SsaImpl.qll
+++ b/powershell/ql/lib/semmle/code/powershell/dataflow/internal/SsaImpl.qll
@@ -179,39 +179,12 @@ private module Cached {
 
 import Cached
 
-/**
- * An extended static single assignment (SSA) definition.
- *
- * This is either a normal SSA definition (`Definition`) or a
- * phi-read node (`PhiReadNode`).
- *
- * Only intended for internal use.
- */
-class DefinitionExt extends Impl::DefinitionExt {
-  VarReadAccessCfgNode getARead() { result = getARead(this) }
-
-  override string toString() { result = this.(Ssa::Definition).toString() }
-
-  override Location getLocation() { result = this.(Ssa::Definition).getLocation() }
-}
-
-/**
- * A phi-read node.
- *
- * Only intended for internal use.
- */
-class PhiReadNode extends DefinitionExt, Impl::PhiReadNode {
-  override string toString() { result = "SSA phi read(" + this.getSourceVariable() + ")" }
-
-  override Location getLocation() { result = Impl::PhiReadNode.super.getLocation() }
-}
-
 /** Gets the SSA definition node corresponding to parameter `p`. */
 pragma[nomagic]
-DefinitionExt getParameterDef(Parameter p) {
+Definition getParameterDef(Parameter p) {
   exists(Cfg::BasicBlock bb, int i |
     bb.getNode(i).getAstNode() = p and
-    result.definesAt(_, bb, i, _)
+    result.definesAt(_, bb, i)
   )
 }