diff --git a/nix-js/runtime-ts/src/helpers.ts b/nix-js/runtime-ts/src/helpers.ts
index 8734f9a..1128a28 100644
--- a/nix-js/runtime-ts/src/helpers.ts
+++ b/nix-js/runtime-ts/src/helpers.ts
@@ -84,23 +84,20 @@ export const withContext = <T>(message: string, span: string, fn: () => T): T =>
  * - Path mode: Store contexts are forbidden (will throw error)
  * - String mode: All contexts are preserved and merged
  *
- * If first element is a path, result is a path (with constraint: no store context allowed)
- *
  * @param parts - Array of values to concatenate
+ * @param forceString - If true, result is always a string (paths are copied to store)
  * @returns String or Path with merged contexts from all parts
  */
-export const concatStringsWithContext = (parts: NixValue[]): NixString | NixPath => {
+export const concatStringsWithContext = (parts: NixValue[], forceString: boolean): NixString | NixPath => {
   if (parts.length === 0) {
     return "";
   }
 
   const forced = parts.map(force);
 
-  // Check if first element is a path
-  const firstIsPath = isNixPath(forced[0]);
+  const firstIsPath = !forceString && isNixPath(forced[0]);
 
   if (firstIsPath) {
-    // Path concatenation mode: result will be a path
     let result = (forced[0] as NixPath).value;
 
     for (let i = 1; i < forced.length; i++) {
@@ -111,13 +108,11 @@ export const concatStringsWithContext = (parts: NixValue[]): NixString | NixPath
       } else if (typeof part === "string") {
         result += part;
       } else if (isStringWithContext(part)) {
-        // Lix constraint: cannot mix store context with paths
         if (part.context.size > 0) {
           throw new TypeError("a string that refers to a store path cannot be appended to a path");
         }
         result += part.value;
       } else {
-        // Coerce to string
         const tempContext: NixStringContext = new Set();
         const coerced = coerceToString(part, StringCoercionMode.Interpolation, false, tempContext);
 
@@ -132,19 +127,15 @@ export const concatStringsWithContext = (parts: NixValue[]): NixString | NixPath
     return mkPath(result);
   }
 
-  // String concatenation mode
-  // Note: firstIsPath is already false at this point, otherwise we would have
-  // returned in the path concatenation branch above
   const context: NixStringContext = new Set();
   const strParts: string[] = [];
 
-  for (const part of parts) {
-    const forced = force(part);
-    if (isNixPath(forced)) {
-      const str = coerceToString(forced, StringCoercionMode.Interpolation, true, context);
+  for (const part of forced) {
+    if (isNixPath(part)) {
+      const str = coerceToString(part, StringCoercionMode.Interpolation, true, context);
       strParts.push(str);
     } else {
-      const str = coerceToString(forced, StringCoercionMode.Interpolation, false, context);
+      const str = coerceToString(part, StringCoercionMode.Interpolation, false, context);
       strParts.push(str);
     }
   }
diff --git a/nix-js/runtime-ts/src/string-context.ts b/nix-js/runtime-ts/src/string-context.ts
index 2da8a04..0c6e20c 100644
--- a/nix-js/runtime-ts/src/string-context.ts
+++ b/nix-js/runtime-ts/src/string-context.ts
@@ -165,6 +165,10 @@ export const parseContextToInfoMap = (context: NixStringContext): Map<string, Pa
     }
   }
 
+  for (const info of result.values()) {
+    info.outputs.sort();
+  }
+
   return result;
 };
 
diff --git a/nix-js/src/codegen.rs b/nix-js/src/codegen.rs
index d2b168c..7e909f1 100644
--- a/nix-js/src/codegen.rs
+++ b/nix-js/src/codegen.rs
@@ -141,6 +141,12 @@ impl<Ctx: CodegenContext> Compile<Ctx> for usize {
     }
 }
 
+impl<Ctx: CodegenContext> Compile<Ctx> for bool {
+    fn compile(&self, _ctx: &Ctx, buf: &mut CodeBuffer) {
+        let _ = write!(buf, "{self}");
+    }
+}
+
 impl<Ctx: CodegenContext> Compile<Ctx> for Quoted<'_> {
     fn compile(&self, ctx: &Ctx, buf: &mut CodeBuffer) {
         code!(buf, ctx; "\"" escaped(self.0) "\"")
@@ -616,7 +622,7 @@ impl<Ctx: CodegenContext> Compile<Ctx> for ConcatStrings {
                     "Nix.withContext(\"while evaluating a path segment\"," part.span() ",()=>(" part "))"
                 );
             })
-            "])"
+            "]," self.force_string ")"
         );
     }
 }
diff --git a/nix-js/src/ir.rs b/nix-js/src/ir.rs
index c0740c7..b0fe989 100644
--- a/nix-js/src/ir.rs
+++ b/nix-js/src/ir.rs
@@ -64,7 +64,7 @@ ir! {
     If { pub cond: ExprId, pub consq: ExprId, pub alter: ExprId },
     Call { pub func: ExprId, pub arg: ExprId },
     Assert { pub assertion: ExprId, pub expr: ExprId, pub assertion_raw: String },
-    ConcatStrings { pub parts: Vec<ExprId> },
+    ConcatStrings { pub parts: Vec<ExprId>, pub force_string: bool },
     Path { pub expr: ExprId },
     Func { pub body: ExprId, pub param: Option<Param>, pub arg: ExprId, pub thunks: Vec<(ExprId, ExprId)> },
     TopLevel { pub body: ExprId, pub thunks: Vec<(ExprId, ExprId)> },
diff --git a/nix-js/src/ir/downgrade.rs b/nix-js/src/ir/downgrade.rs
index b11496d..23f03bf 100644
--- a/nix-js/src/ir/downgrade.rs
+++ b/nix-js/src/ir/downgrade.rs
@@ -139,7 +139,7 @@ impl<Ctx: DowngradeContext> Downgrade<Ctx> for ast::Path {
                 part
             }
         } else {
-            ctx.new_expr(ConcatStrings { parts, span }.to_ir())
+            ctx.new_expr(ConcatStrings { parts, span, force_string: false }.to_ir())
         };
         Ok(ctx.new_expr(Path { expr, span }.to_ir()))
     }
@@ -166,7 +166,7 @@ impl<Ctx: DowngradeContext> Downgrade<Ctx> for ast::Str {
         Ok(if is_single_literal {
             parts.into_iter().next().unwrap()
         } else {
-            ctx.new_expr(ConcatStrings { parts, span }.to_ir())
+            ctx.new_expr(ConcatStrings { parts, span, force_string: true }.to_ir())
         })
     }
 }
diff --git a/nix-js/src/ir/utils.rs b/nix-js/src/ir/utils.rs
index fc01f0d..40c4baa 100644
--- a/nix-js/src/ir/utils.rs
+++ b/nix-js/src/ir/utils.rs
@@ -442,7 +442,7 @@ pub fn downgrade_attr(attr: ast::Attr, ctx: &mut impl DowngradeContext) -> Resul
                     })
                     .collect::<Result<Vec<_>>>()?;
                 Ok(Attr::Dynamic(
-                    ctx.new_expr(ConcatStrings { parts, span }.to_ir()),
+                    ctx.new_expr(ConcatStrings { parts, span, force_string: true }.to_ir()),
                     span,
                 ))
             }