diff --git a/interpreter.c b/interpreter.c
index 55a9c94..588a730 100644
--- a/interpreter.c
+++ b/interpreter.c
@@ -3257,13 +3257,14 @@ ReturnObject *interpretAssignmentStmtNode(StmtNode *node,
 {
 	AssignmentStmtNode *stmt = (AssignmentStmtNode *)node->stmt;
 	ValueObject *val = interpretExprNode(stmt->expr, scope);
+	if (!val) return NULL;
 	/* interpolate assigned strings */
 	if (val->type == VT_STRING) {
 		ValueObject *use = castStringImplicit(val, scope);
 		deleteValueObject(val);
+		if (!use) return NULL;
 		val = use;
 	}
-	if (!val) return NULL;
 	if (!updateScopeValue(scope, scope, stmt->target, val)) {
 		deleteValueObject(val);
 		return NULL;