diff --git a/Ghidra/Framework/SoftwareModeling/src/main/java/ghidra/program/model/data/FunctionDefinitionDataType.java b/Ghidra/Framework/SoftwareModeling/src/main/java/ghidra/program/model/data/FunctionDefinitionDataType.java
index f4ca1e0168..c40471bcef 100644
--- a/Ghidra/Framework/SoftwareModeling/src/main/java/ghidra/program/model/data/FunctionDefinitionDataType.java
+++ b/Ghidra/Framework/SoftwareModeling/src/main/java/ghidra/program/model/data/FunctionDefinitionDataType.java
@@ -189,7 +189,7 @@ public class FunctionDefinitionDataType extends GenericDataType implements Funct
 
 		if (GenericCallingConvention
 				.getGenericCallingConvention(conventionName) == GenericCallingConvention.unknown &&
-			!dataMgr.getKnownCallingConventionNames().contains(name)) {
+			(dataMgr == null || !dataMgr.getKnownCallingConventionNames().contains(name))) {
 			throw new InvalidInputException("Unknown calling convention name: " + conventionName);
 		}