diff --git a/modules/nf-lang/src/main/java/nextflow/script/control/ProcessToGroovyVisitorV1.java b/modules/nf-lang/src/main/java/nextflow/script/control/ProcessToGroovyVisitorV1.java
index 19988b1b34..e0263a824d 100644
--- a/modules/nf-lang/src/main/java/nextflow/script/control/ProcessToGroovyVisitorV1.java
+++ b/modules/nf-lang/src/main/java/nextflow/script/control/ProcessToGroovyVisitorV1.java
@@ -68,7 +68,8 @@ public Statement transform(ProcessNodeV1 node) {
                 args(
                     closureX(null, node.exec),
                     constX(sgh.getSourceText(node.exec)),
-                    constX(node.type)
+                    constX(node.type),
+                    sgh.getVariableRefs(node.exec)
                 )
             ))
         )));
diff --git a/modules/nf-lang/src/main/java/nextflow/script/control/ProcessToGroovyVisitorV2.java b/modules/nf-lang/src/main/java/nextflow/script/control/ProcessToGroovyVisitorV2.java
index 58b13c7a47..11b645fe41 100644
--- a/modules/nf-lang/src/main/java/nextflow/script/control/ProcessToGroovyVisitorV2.java
+++ b/modules/nf-lang/src/main/java/nextflow/script/control/ProcessToGroovyVisitorV2.java
@@ -91,7 +91,8 @@ public Statement transform(ProcessNodeV2 node) {
                 args(
                     closureX(node.exec),
                     constX(sgh.getSourceText(node.exec)),
-                    constX(node.type)
+                    constX(node.type),
+                    sgh.getVariableRefs(node.exec)
                 )
             ))
         )));
diff --git a/modules/nf-lang/src/main/java/nextflow/script/control/ScriptToGroovyHelper.java b/modules/nf-lang/src/main/java/nextflow/script/control/ScriptToGroovyHelper.java
index 467c9c8c04..e9f44c49e3 100644
--- a/modules/nf-lang/src/main/java/nextflow/script/control/ScriptToGroovyHelper.java
+++ b/modules/nf-lang/src/main/java/nextflow/script/control/ScriptToGroovyHelper.java
@@ -15,6 +15,8 @@
  */
 package nextflow.script.control;
 
+import java.util.ArrayList;
+import java.util.Collections;
 import java.util.HashSet;
 import java.util.Set;
 
@@ -22,10 +24,12 @@
 import org.codehaus.groovy.ast.Variable;
 import org.codehaus.groovy.ast.expr.ClosureExpression;
 import org.codehaus.groovy.ast.expr.Expression;
+import org.codehaus.groovy.ast.expr.PropertyExpression;
 import org.codehaus.groovy.ast.expr.VariableExpression;
 import org.codehaus.groovy.ast.stmt.Statement;
 import org.codehaus.groovy.control.SourceUnit;
 
+import static nextflow.script.ast.ASTUtils.*;
 import static org.codehaus.groovy.ast.tools.GeneralUtils.*;
 
 /**
@@ -41,6 +45,75 @@ public ScriptToGroovyHelper(SourceUnit sourceUnit) {
         this.sourceUnit = sourceUnit;
     }
 
+    /**
+     * Get the list of variable references in a statement.
+     *
+     * This method is used to collect references to task ext
+     * properties (e.g. `task.ext.args`) in the process body, so that
+     * they are included in the task hash.
+     *
+     * These properties are typically used like inputs, but are not
+     * explicitly declared, so they must be identified by their usage.
+     *
+     * The resulting list expression should be provided as the fourth
+     * argument of the BodyDef constructor.
+     *
+     * @param node
+     */
+    public Expression getVariableRefs(Statement node) {
+        var refs = new VariableRefCollector().collect(node).stream()
+            .map(name -> createX("nextflow.script.TokenValRef", constX(name)))
+            .toList();
+
+        return listX(refs);
+    }
+
+    private class VariableRefCollector extends CodeVisitorSupport {
+
+        private Set<String> variableRefs;
+
+        public Set<String> collect(Statement node) {
+            variableRefs = new HashSet<>();
+            visit(node);
+            return variableRefs;
+        }
+
+        @Override
+        public void visitPropertyExpression(PropertyExpression node) {
+            if( !isPropertyChain(node) ) {
+                super.visitPropertyExpression(node);
+                return;
+            }
+
+            var name = asPropertyChain(node);
+            if( name.startsWith("task.ext.") )
+                variableRefs.add(name);
+        }
+
+        private static boolean isPropertyChain(PropertyExpression node) {
+            var target = node.getObjectExpression();
+            while( target instanceof PropertyExpression pe )
+                target = pe.getObjectExpression();
+            return target instanceof VariableExpression;
+        }
+
+        private static String asPropertyChain(PropertyExpression node) {
+            var list = new ArrayList<String>();
+            list.add(node.getPropertyAsString());
+
+            var target = node.getObjectExpression();
+            while( target instanceof PropertyExpression pe ) {
+                list.add(pe.getPropertyAsString());
+                target = pe.getObjectExpression();
+            }
+
+            list.add(target.getText());
+
+            Collections.reverse(list);
+            return String.join(".", list);
+        }
+    }
+
     /**
      * Transform an expression into a lazy expression by
      * wrapping it in a closure if it references variables.
diff --git a/tests/checks/task-ext.nf/.checks b/tests/checks/task-ext.nf/.checks
new file mode 100644
index 0000000000..2e976fb1d2
--- /dev/null
+++ b/tests/checks/task-ext.nf/.checks
@@ -0,0 +1,30 @@
+set -e
+
+#
+# initial run
+#
+$NXF_RUN -c ../../task-ext.config --value foo | tee .stdout
+
+[[ `grep INFO .nextflow.log | grep -c 'Submitted process'` == 1 ]] || false
+
+grep 'args = --some-param foo' .stdout
+
+
+#
+# resumed run (same value)
+#
+$NXF_RUN -c ../../task-ext.config --value foo -resume | tee .stdout
+
+[[ `grep INFO .nextflow.log | grep -c 'Cached process'` == 1 ]] || false
+
+grep 'args = --some-param foo' .stdout
+
+
+#
+# resumed run (new value)
+#
+$NXF_RUN -c ../../task-ext.config --value bar -resume | tee .stdout
+
+[[ `grep INFO .nextflow.log | grep -c 'Submitted process'` == 1 ]] || false
+
+grep 'args = --some-param bar' .stdout
diff --git a/tests/task-ext.config b/tests/task-ext.config
new file mode 100644
index 0000000000..e19aae3bb1
--- /dev/null
+++ b/tests/task-ext.config
@@ -0,0 +1,10 @@
+
+params {
+    value = 'value'
+}
+
+process {
+    withName: 'HELLO' {
+        ext.args = "--some-param ${params.value}"
+    }
+}
diff --git a/tests/task-ext.nf b/tests/task-ext.nf
new file mode 100644
index 0000000000..ba2519e4b7
--- /dev/null
+++ b/tests/task-ext.nf
@@ -0,0 +1,13 @@
+
+process HELLO {
+    debug true
+
+    script:
+    """
+    echo "args = ${task.ext.args}"
+    """
+}
+
+workflow {
+    HELLO()
+}