diff --git a/kernel/fstdata.cc b/kernel/fstdata.cc
index dd88590b2..f2e73e9ec 100644
--- a/kernel/fstdata.cc
+++ b/kernel/fstdata.cc
@@ -397,7 +397,7 @@ int FstData::getWidth(fstHandle signal)
 }
 
 // Auto-discover scope from FST by finding the top module
-std::vector<std::string> FstData::autoScope(Module *topmod) {	
+std::string FstData::autoScope(Module *topmod) {
 
 	log("Auto-discovering scopes from file...\n");
 	std::string top = RTLIL::unescape_id(topmod->name);
@@ -449,11 +449,17 @@ std::vector<std::string> FstData::autoScope(Module *topmod) {
 	if (results.empty()) {
 		log_warning("Could not auto-discover scope for module '%s'...\n", 
 			RTLIL::unescape_id(topmod->name).c_str());
+		return "";
 	} else {
 		log("Found %d scopes for module '%s':\n", GetSize(results), RTLIL::unescape_id(topmod->name).c_str());
 		for (const auto& scope : results) {
 			log("  %s\n", scope.c_str());
 		}
+		if (results.size() > 1) {
+			log_warning("Multiple scopes found for module '%s'. Using the first one.\n", 
+				RTLIL::unescape_id(topmod->name).c_str());
+		}
+		std::string scope = results[0];
 	}
-	return results;
+	return scope;
 }
diff --git a/kernel/fstdata.h b/kernel/fstdata.h
index 01e175691..f95806cca 100644
--- a/kernel/fstdata.h
+++ b/kernel/fstdata.h
@@ -58,7 +58,7 @@ class FstData
 	double getTimescale() { return timescale; }
 	const char *getTimescaleString() { return timescale_str.c_str(); }
 	int getWidth(fstHandle signal);
-	std::vector<std::string> autoScope(Module *topmod);
+	std::string autoScope(Module *topmod);
 private:
 	void extractVarNames();
 
diff --git a/passes/sat/sim.cc b/passes/sat/sim.cc
index 00b144037..113a15bdd 100644
--- a/passes/sat/sim.cc
+++ b/passes/sat/sim.cc
@@ -1475,12 +1475,11 @@ struct SimWorker : SimShared
 		fst = new FstData(sim_filename);
 		timescale = fst->getTimescaleString();
 		if (scope.empty()) {
-			std::vector<std::string> scopes = fst->autoScope(topmod);
-			if (scopes.empty()) {
+			scope = fst->autoScope(topmod);
+			if (scope.empty()) {
 				log_error("No scope found for module '%s'. Please specify -scope explicitly.\n", 
 					RTLIL::unescape_id(topmod->name).c_str());
 			}
-			scope = scopes[0]; // Use the first scope found by default
 		}
 		log("Using scope: \"%s\"\n", scope.c_str());
 
diff --git a/passes/silimate/reg_rename.cc b/passes/silimate/reg_rename.cc
index e5c7ffca2..5635b6869 100644
--- a/passes/silimate/reg_rename.cc
+++ b/passes/silimate/reg_rename.cc
@@ -200,12 +200,11 @@ struct RegRenamePass : public Pass {
 			try {
 				FstData fst(vcd_filename);
 				if (scope.empty()) {
-					std::vector<std::string> scopes = fst.autoScope(topmod);
-					if (scopes.empty()) {
+					scope = fst.autoScope(topmod);
+					if (scope.empty()) {
 						log_error("No scope found for module '%s'. Please specify -scope explicitly.\n", 
 							RTLIL::unescape_id(topmod->name).c_str());
 					}
-					scope = scopes[0]; // Use the first scope found by default
 				}
 				log("Using scope: \"%s\"\n", scope.c_str());
 				for (auto &var : fst.getVars()) {