diff --git a/Ghidra/Framework/SoftwareModeling/src/main/java/ghidra/program/database/SpecExtension.java b/Ghidra/Framework/SoftwareModeling/src/main/java/ghidra/program/database/SpecExtension.java
index 0b2ee72704..01372bef38 100644
--- a/Ghidra/Framework/SoftwareModeling/src/main/java/ghidra/program/database/SpecExtension.java
+++ b/Ghidra/Framework/SoftwareModeling/src/main/java/ghidra/program/database/SpecExtension.java
@@ -637,7 +637,13 @@ public class SpecExtension {
 		}
 		cspecValidator.verify(res.optionName, document);
 		checkExtension(res);
-		parseExtension(res.optionName, document, program.getCompilerSpec(), false);
+		if (!(program.getCompilerSpec() instanceof BasicCompilerSpec)) {
+			throw new SleighException(
+				"Can only test specification extensions against SLEIGH program");
+		}
+		BasicCompilerSpec cSpecCopy =
+			new BasicCompilerSpec((BasicCompilerSpec) program.getCompilerSpec());
+		parseExtension(res.optionName, document, cSpecCopy, false);
 		return res;
 	}
 
diff --git a/Ghidra/Framework/SoftwareModeling/src/main/java/ghidra/program/model/lang/BasicCompilerSpec.java b/Ghidra/Framework/SoftwareModeling/src/main/java/ghidra/program/model/lang/BasicCompilerSpec.java
index 6f82352b27..56e457fddd 100644
--- a/Ghidra/Framework/SoftwareModeling/src/main/java/ghidra/program/model/lang/BasicCompilerSpec.java
+++ b/Ghidra/Framework/SoftwareModeling/src/main/java/ghidra/program/model/lang/BasicCompilerSpec.java
@@ -163,7 +163,7 @@ public class BasicCompilerSpec implements CompilerSpec {
 	 * spec from Language.
 	 * @param op2 is the spec to clone
 	 */
-	protected BasicCompilerSpec(BasicCompilerSpec op2) {
+	public BasicCompilerSpec(BasicCompilerSpec op2) {
 		language = op2.language;
 		description = op2.description;
 		// PrototypeModel is immutable but the map may change, so callingConventionMap