diff --git a/c/cert/src/rules/EXP39-C/DoNotAccessVariableViaPointerOfIncompatibleType.ql b/c/cert/src/rules/EXP39-C/DoNotAccessVariableViaPointerOfIncompatibleType.ql
index 856cad1d58..23e3a94de7 100644
--- a/c/cert/src/rules/EXP39-C/DoNotAccessVariableViaPointerOfIncompatibleType.ql
+++ b/c/cert/src/rules/EXP39-C/DoNotAccessVariableViaPointerOfIncompatibleType.ql
@@ -18,7 +18,7 @@
 
 import cpp
 import codingstandards.c.cert
-import semmle.code.cpp.dataflow.DataFlow
+import semmle.code.cpp.dataflow.new.DataFlow
 import semmle.code.cpp.controlflow.Dominance
 import IndirectCastFlow::PathGraph
 
@@ -35,12 +35,12 @@ class MemsetFunction extends Function {
   }
 }
 
-class IndirectCastAnalysisUnconvertedCastExpr extends Expr {
-  IndirectCastAnalysisUnconvertedCastExpr() { this = any(Cast c).getUnconverted() }
+class CastedExpr extends Expr {
+  CastedExpr() { this = any(Cast c).getExpr() }
 }
 
-class IndirectCastAnalysisDereferenceSink extends Expr {
-  IndirectCastAnalysisDereferenceSink() { dereferenced(this) }
+class DereferencedExpr extends Expr {
+  DereferencedExpr() { dereferenced(this) }
 }
 
 class ReallocationFunction extends AllocationFunction {
@@ -68,14 +68,14 @@ module IndirectCastConfig implements DataFlow::StateConfigSig {
 
   predicate isSource(DataFlow::Node source, FlowState state) {
     state instanceof IndirectCastDefaultFlowState and
-    source.asExpr() instanceof IndirectCastAnalysisUnconvertedCastExpr
+    source.asExpr() instanceof CastedExpr
   }
 
   predicate isSink(DataFlow::Node sink, FlowState state) {
-    sink.asExpr() instanceof IndirectCastAnalysisUnconvertedCastExpr and
+    sink.asExpr() instanceof CastedExpr and
     state instanceof IndirectCastDefaultFlowState
     or
-    sink.asExpr() instanceof IndirectCastAnalysisDereferenceSink and
+    sink.asExpr() instanceof DereferencedExpr and
     state instanceof IndirectCastReallocatedFlowState and
     // The memset call won't always have an edge to subsequent dereferences.
     //
@@ -193,17 +193,18 @@ Type compatibleTypes(Type type) {
 }
 
 from
-  IndirectCastFlow::PathNode source, IndirectCastFlow::PathNode sink, Cast cast, Type fromType,
-  Type toType
+  Expr sinkExpr, IndirectCastFlow::PathNode source, IndirectCastFlow::PathNode sink, Cast cast,
+  Type fromType, Type toType
 where
-  not isExcluded(sink.getNode().asExpr(),
-    Pointers3Package::doNotAccessVariableViaPointerOfIncompatibleTypeQuery()) and
+  not isExcluded(sinkExpr, Pointers3Package::doNotAccessVariableViaPointerOfIncompatibleTypeQuery()) and
   cast.getFile().compiledAsC() and
   IndirectCastFlow::flowPath(source, sink) and
   // include only sinks which are not a compatible type to the associated source
   source.getNode().asExpr() = cast.getUnconverted() and
   fromType = cast.getUnconverted().getType().(PointerType).getBaseType() and
   toType = sink.getNode().asExpr().getActualType().(PointerType).getBaseType() and
-  not toType = compatibleTypes(fromType)
-select sink.getNode().asExpr().getUnconverted(), source, sink,
+  not toType = compatibleTypes(fromType) and
+  sinkExpr = sink.getNode().asExpr() and
+  (sinkExpr instanceof CastedExpr or sinkExpr instanceof DereferencedExpr)
+select sinkExpr, source, sink,
   "Cast from " + fromType + " to " + toType + " results in an incompatible pointer base type."
diff --git a/c/cert/test/rules/EXP39-C/DoNotAccessVariableViaPointerOfIncompatibleType.expected b/c/cert/test/rules/EXP39-C/DoNotAccessVariableViaPointerOfIncompatibleType.expected
index 381e409d2a..3f16fe6eb7 100644
--- a/c/cert/test/rules/EXP39-C/DoNotAccessVariableViaPointerOfIncompatibleType.expected
+++ b/c/cert/test/rules/EXP39-C/DoNotAccessVariableViaPointerOfIncompatibleType.expected
@@ -1,67 +1,69 @@
-WARNING: module 'DataFlow' has been deprecated and may be removed in future (DoNotAccessVariableViaPointerOfIncompatibleType.ql:66,38-46)
-WARNING: module 'DataFlow' has been deprecated and may be removed in future (DoNotAccessVariableViaPointerOfIncompatibleType.ql:69,22-30)
-WARNING: module 'DataFlow' has been deprecated and may be removed in future (DoNotAccessVariableViaPointerOfIncompatibleType.ql:74,20-28)
-WARNING: module 'DataFlow' has been deprecated and may be removed in future (DoNotAccessVariableViaPointerOfIncompatibleType.ql:107,23-31)
-WARNING: module 'DataFlow' has been deprecated and may be removed in future (DoNotAccessVariableViaPointerOfIncompatibleType.ql:116,5-13)
-WARNING: module 'DataFlow' has been deprecated and may be removed in future (DoNotAccessVariableViaPointerOfIncompatibleType.ql:116,45-53)
-WARNING: module 'DataFlow' has been deprecated and may be removed in future (DoNotAccessVariableViaPointerOfIncompatibleType.ql:138,27-35)
 edges
-| test.c:49:8:49:9 | s3 | test.c:50:8:50:9 | s1 | provenance |  |
+| test.c:49:3:49:9 | ... = ... | test.c:50:8:50:9 | s1 | provenance |  |
+| test.c:49:8:49:9 | s3 | test.c:49:3:49:9 | ... = ... | provenance |  |
+| test.c:60:16:60:18 | E1A | test.c:60:16:60:18 | E1A | provenance |  |
 | test.c:60:16:60:18 | E1A | test.c:61:16:61:17 | e1 | provenance |  |
-| test.c:60:16:60:18 | E1A | test.c:65:10:65:12 | & ... | provenance |  |
-| test.c:68:22:68:22 | v | test.c:68:41:68:41 | v | provenance |  |
+| test.c:68:22:68:22 | v | test.c:68:34:68:41 | v | provenance |  |
 | test.c:72:13:72:15 | & ... | test.c:68:22:68:22 | v | provenance |  |
 | test.c:74:13:74:15 | & ... | test.c:68:22:68:22 | v | provenance |  |
-| test.c:97:32:97:37 | call to malloc | test.c:98:40:98:41 | s2 | provenance |  |
-| test.c:97:32:97:37 | call to malloc | test.c:98:40:98:41 | s2 | provenance |  |
-| test.c:98:32:98:38 | call to realloc | test.c:99:3:99:4 | s3 | provenance |  |
-| test.c:98:32:98:38 | call to realloc | test.c:100:10:100:11 | s3 | provenance |  |
-| test.c:98:40:98:41 | s2 | test.c:98:32:98:38 | call to realloc | provenance | Config |
+| test.c:97:19:97:56 | call to malloc | test.c:97:19:97:56 | call to malloc | provenance |  |
+| test.c:97:19:97:56 | call to malloc | test.c:98:40:98:41 | s2 | provenance |  |
+| test.c:97:19:97:56 | call to malloc | test.c:98:40:98:41 | s2 | provenance |  |
+| test.c:98:19:98:61 | call to realloc | test.c:98:19:98:61 | call to realloc | provenance |  |
+| test.c:98:19:98:61 | call to realloc | test.c:98:19:98:61 | call to realloc | provenance |  |
+| test.c:98:19:98:61 | call to realloc | test.c:99:3:99:4 | s3 | provenance |  |
+| test.c:98:19:98:61 | call to realloc | test.c:100:10:100:11 | s3 | provenance |  |
+| test.c:98:40:98:41 | s2 | test.c:98:19:98:61 | call to realloc | provenance | Config |
 nodes
-| test.c:6:19:6:20 | & ... | semmle.label | & ... |
-| test.c:11:10:11:11 | & ... | semmle.label | & ... |
-| test.c:13:17:13:19 | & ... | semmle.label | & ... |
-| test.c:15:17:15:19 | & ... | semmle.label | & ... |
-| test.c:19:18:19:20 | & ... | semmle.label | & ... |
-| test.c:20:20:20:22 | & ... | semmle.label | & ... |
-| test.c:22:11:22:13 | & ... | semmle.label | & ... |
-| test.c:27:17:27:19 | & ... | semmle.label | & ... |
-| test.c:28:10:28:12 | & ... | semmle.label | & ... |
-| test.c:29:13:29:15 | & ... | semmle.label | & ... |
-| test.c:30:19:30:21 | & ... | semmle.label | & ... |
-| test.c:31:16:31:18 | & ... | semmle.label | & ... |
+| test.c:6:12:6:20 | & ... | semmle.label | & ... |
+| test.c:11:3:11:11 | & ... | semmle.label | & ... |
+| test.c:13:3:13:19 | & ... | semmle.label | & ... |
+| test.c:15:3:15:19 | & ... | semmle.label | & ... |
+| test.c:19:3:19:20 | & ... | semmle.label | & ... |
+| test.c:20:3:20:22 | & ... | semmle.label | & ... |
+| test.c:22:3:22:13 | & ... | semmle.label | & ... |
+| test.c:27:3:27:19 | & ... | semmle.label | & ... |
+| test.c:28:3:28:12 | & ... | semmle.label | & ... |
+| test.c:29:3:29:15 | & ... | semmle.label | & ... |
+| test.c:30:3:30:21 | & ... | semmle.label | & ... |
+| test.c:31:3:31:18 | & ... | semmle.label | & ... |
 | test.c:47:8:47:9 | s2 | semmle.label | s2 |
+| test.c:49:3:49:9 | ... = ... | semmle.label | ... = ... |
 | test.c:49:8:49:9 | s3 | semmle.label | s3 |
 | test.c:49:8:49:9 | s3 | semmle.label | s3 |
 | test.c:50:8:50:9 | s1 | semmle.label | s1 |
 | test.c:60:16:60:18 | E1A | semmle.label | E1A |
 | test.c:60:16:60:18 | E1A | semmle.label | E1A |
+| test.c:60:16:60:18 | E1A | semmle.label | E1A |
 | test.c:61:16:61:17 | e1 | semmle.label | e1 |
-| test.c:65:10:65:12 | & ... | semmle.label | & ... |
+| test.c:65:3:65:12 | & ... | semmle.label | & ... |
 | test.c:68:22:68:22 | v | semmle.label | v |
-| test.c:68:41:68:41 | v | semmle.label | v |
+| test.c:68:34:68:41 | v | semmle.label | v |
 | test.c:72:13:72:15 | & ... | semmle.label | & ... |
 | test.c:72:13:72:15 | & ... | semmle.label | & ... |
 | test.c:74:13:74:15 | & ... | semmle.label | & ... |
 | test.c:74:13:74:15 | & ... | semmle.label | & ... |
-| test.c:97:32:97:37 | call to malloc | semmle.label | call to malloc |
-| test.c:97:32:97:37 | call to malloc | semmle.label | call to malloc |
-| test.c:98:32:98:38 | call to realloc | semmle.label | call to realloc |
-| test.c:98:32:98:38 | call to realloc | semmle.label | call to realloc |
-| test.c:98:32:98:38 | call to realloc | semmle.label | call to realloc |
+| test.c:97:19:97:56 | call to malloc | semmle.label | call to malloc |
+| test.c:97:19:97:56 | call to malloc | semmle.label | call to malloc |
+| test.c:97:19:97:56 | call to malloc | semmle.label | call to malloc |
+| test.c:98:19:98:61 | call to realloc | semmle.label | call to realloc |
+| test.c:98:19:98:61 | call to realloc | semmle.label | call to realloc |
+| test.c:98:19:98:61 | call to realloc | semmle.label | call to realloc |
+| test.c:98:19:98:61 | call to realloc | semmle.label | call to realloc |
+| test.c:98:19:98:61 | call to realloc | semmle.label | call to realloc |
 | test.c:98:40:98:41 | s2 | semmle.label | s2 |
 | test.c:98:40:98:41 | s2 | semmle.label | s2 |
 | test.c:99:3:99:4 | s3 | semmle.label | s3 |
 | test.c:100:10:100:11 | s3 | semmle.label | s3 |
 subpaths
 #select
-| test.c:6:19:6:20 | & ... | test.c:6:19:6:20 | & ... | test.c:6:19:6:20 | & ... | Cast from float to int results in an incompatible pointer base type. |
-| test.c:11:10:11:11 | & ... | test.c:11:10:11:11 | & ... | test.c:11:10:11:11 | & ... | Cast from short[2] to int results in an incompatible pointer base type. |
-| test.c:13:17:13:19 | & ... | test.c:13:17:13:19 | & ... | test.c:13:17:13:19 | & ... | Cast from short[2] to short[4] results in an incompatible pointer base type. |
-| test.c:19:18:19:20 | & ... | test.c:19:18:19:20 | & ... | test.c:19:18:19:20 | & ... | Cast from char to signed char results in an incompatible pointer base type. |
-| test.c:30:19:30:21 | & ... | test.c:30:19:30:21 | & ... | test.c:30:19:30:21 | & ... | Cast from int to unsigned int results in an incompatible pointer base type. |
+| test.c:6:19:6:20 | & ... | test.c:6:12:6:20 | & ... | test.c:6:12:6:20 | & ... | Cast from float to int results in an incompatible pointer base type. |
+| test.c:11:10:11:11 | & ... | test.c:11:3:11:11 | & ... | test.c:11:3:11:11 | & ... | Cast from short[2] to int results in an incompatible pointer base type. |
+| test.c:13:17:13:19 | & ... | test.c:13:3:13:19 | & ... | test.c:13:3:13:19 | & ... | Cast from short[2] to short[4] results in an incompatible pointer base type. |
+| test.c:19:18:19:20 | & ... | test.c:19:3:19:20 | & ... | test.c:19:3:19:20 | & ... | Cast from char to signed char results in an incompatible pointer base type. |
+| test.c:30:19:30:21 | & ... | test.c:30:3:30:21 | & ... | test.c:30:3:30:21 | & ... | Cast from int to unsigned int results in an incompatible pointer base type. |
 | test.c:47:8:47:9 | s2 | test.c:47:8:47:9 | s2 | test.c:47:8:47:9 | s2 | Cast from (unnamed class/struct/union) to (unnamed class/struct/union) results in an incompatible pointer base type. |
 | test.c:49:8:49:9 | s3 | test.c:49:8:49:9 | s3 | test.c:49:8:49:9 | s3 | Cast from S1 to (unnamed class/struct/union) results in an incompatible pointer base type. |
 | test.c:50:8:50:9 | s1 | test.c:50:8:50:9 | s1 | test.c:50:8:50:9 | s1 | Cast from (unnamed class/struct/union) to S1 results in an incompatible pointer base type. |
-| test.c:68:41:68:41 | v | test.c:72:13:72:15 | & ... | test.c:68:41:68:41 | v | Cast from float to int results in an incompatible pointer base type. |
+| test.c:68:41:68:41 | v | test.c:72:13:72:15 | & ... | test.c:68:34:68:41 | v | Cast from float to int results in an incompatible pointer base type. |
 | test.c:99:3:99:4 | s3 | test.c:98:40:98:41 | s2 | test.c:99:3:99:4 | s3 | Cast from S2 to S3 results in an incompatible pointer base type. |
diff --git a/change_notes/2026-09-20-update-exp39-c-to-use-new-dataflow.md b/change_notes/2026-09-20-update-exp39-c-to-use-new-dataflow.md
new file mode 100644
index 0000000000..381d9d3161
--- /dev/null
+++ b/change_notes/2026-09-20-update-exp39-c-to-use-new-dataflow.md
@@ -0,0 +1,3 @@
+ - `EXP39-C` - `DoNotAccessVariableViaPointerOfIncompatibleType.ql`
+   - Updated the underlying dataflow library to use the new dataflow from the deprecated old data flow. This may cause behavioral changes in some analyses, usually with improved results and performance.
+   - Some refactoring required to accommodate functional changes in how dataflow nodes attach to the AST. No functional changes to the analysis from this are expected.
\ No newline at end of file