diff --git a/Ghidra/Features/Base/src/main/java/ghidra/app/plugin/core/function/AbstractEditFunctionSignatureDialog.java b/Ghidra/Features/Base/src/main/java/ghidra/app/plugin/core/function/AbstractEditFunctionSignatureDialog.java
index 43e106e0f1..63d18b1332 100644
--- a/Ghidra/Features/Base/src/main/java/ghidra/app/plugin/core/function/AbstractEditFunctionSignatureDialog.java
+++ b/Ghidra/Features/Base/src/main/java/ghidra/app/plugin/core/function/AbstractEditFunctionSignatureDialog.java
@@ -179,16 +179,12 @@ public abstract class AbstractEditFunctionSignatureDialog extends DialogComponen
 		mainPanel.add(buildSignaturePanel());
 		mainPanel.add(buildAttributePanel());
 		if (allowCallFixup) {
-			installCallFixupWidget(mainPanel);
+			JPanel callFixupPanel = buildCallFixupPanel();
+			mainPanel.add(callFixupPanel != null ? callFixupPanel : buildSpacerPanel());
 		}
 		return mainPanel;
 	}
 
-	private void installCallFixupWidget(JPanel parentPanel) {
-		JPanel callFixupPanel = buildCallFixupPanel();
-		parentPanel.add(callFixupPanel != null ? callFixupPanel : buildSpacerPanel());
-	}
-
 	private JPanel buildSignaturePanel() {
 		JPanel signaturePanel = new JPanel();
 		signaturePanel.setLayout(new BoxLayout(signaturePanel, BoxLayout.X_AXIS));
@@ -252,10 +248,6 @@ public abstract class AbstractEditFunctionSignatureDialog extends DialogComponen
 
 	private JPanel buildCallFixupPanel() {
 
-		if (allowCallFixup) {
-			return null;
-		}
-
 		JPanel callFixupPanel = new JPanel();
 		callFixupPanel.setLayout(new BoxLayout(callFixupPanel, BoxLayout.X_AXIS));
 
diff --git a/Ghidra/Framework/SoftwareModeling/src/test/java/ghidra/program/model/FunctionTestDouble.java b/Ghidra/Framework/SoftwareModeling/src/test/java/ghidra/program/model/FunctionTestDouble.java
index ca9b21eb6e..e7b4344ea2 100644
--- a/Ghidra/Framework/SoftwareModeling/src/test/java/ghidra/program/model/FunctionTestDouble.java
+++ b/Ghidra/Framework/SoftwareModeling/src/test/java/ghidra/program/model/FunctionTestDouble.java
@@ -106,7 +106,7 @@ public class FunctionTestDouble implements Function {
 
 	@Override
 	public String getCallFixup() {
-		throw new UnsupportedOperationException();
+		return null;
 	}
 
 	@Override