diff --git a/Ghidra/Debug/Debugger/src/main/java/ghidra/app/services/TraceRecorder.java b/Ghidra/Debug/Debugger/src/main/java/ghidra/app/services/TraceRecorder.java
index 795b6545cc..29c87640e8 100644
--- a/Ghidra/Debug/Debugger/src/main/java/ghidra/app/services/TraceRecorder.java
+++ b/Ghidra/Debug/Debugger/src/main/java/ghidra/app/services/TraceRecorder.java
@@ -554,6 +554,9 @@ public interface TraceRecorder {
 		TraceMemorySpace regs =
 			getTrace().getMemoryManager().getMemoryRegisterSpace(thread, frameLevel, false);
 		Register parent = isRegisterOnTarget(platform, thread, frameLevel, register);
+		if (parent == null) {
+			throw new IllegalArgumentException("Cannot find register " + register + " on target");
+		}
 		rv = TraceRegisterUtils.combineWithTraceParentRegisterValue(parent, rv, platform, getSnap(),
 			regs, true);
 		return writeThreadRegisters(platform, thread, frameLevel, Map.of(rv.getRegister(), rv));
diff --git a/Ghidra/Debug/Framework-TraceModeling/src/main/java/ghidra/trace/util/TraceRegisterUtils.java b/Ghidra/Debug/Framework-TraceModeling/src/main/java/ghidra/trace/util/TraceRegisterUtils.java
index db7fef1375..24fc51340a 100644
--- a/Ghidra/Debug/Framework-TraceModeling/src/main/java/ghidra/trace/util/TraceRegisterUtils.java
+++ b/Ghidra/Debug/Framework-TraceModeling/src/main/java/ghidra/trace/util/TraceRegisterUtils.java
@@ -154,7 +154,7 @@ public enum TraceRegisterUtils {
 			return rv.getRegisterValue(parent);
 		}
 		if (requireKnown) {
-			if (TraceMemoryState.KNOWN != regs.getState(platform, snap, reg.getBaseRegister())) {
+			if (TraceMemoryState.KNOWN != regs.getState(platform, snap, parent)) {
 				throw new IllegalStateException("Must fetch " + parent + " before setting " + reg);
 			}
 		}