diff --git a/Compiler/src/CostModel.cpp b/Compiler/src/CostModel.cpp
index ce0d5617..593a4bbf 100644
--- a/Compiler/src/CostModel.cpp
+++ b/Compiler/src/CostModel.cpp
@@ -219,7 +219,8 @@ struct CostVisitor : AstVisitor
         }
         else if (AstExprInterpString* expr = node->as<AstExprInterpString>())
         {
-            Cost cost = 0;
+            // Baseline cost of string.format
+            Cost cost = 3;
 
             for (auto innerExpression : expr->expressions)
                 cost += model(innerExpression);