diff --git a/pkgs/build-support/bintools-wrapper/default.nix b/pkgs/build-support/bintools-wrapper/default.nix
index 7ec74a2a92a..fca79636384 100644
--- a/pkgs/build-support/bintools-wrapper/default.nix
+++ b/pkgs/build-support/bintools-wrapper/default.nix
@@ -189,7 +189,7 @@ stdenv.mkDerivation {
       else if targetPlatform.isSparc then "sparc"
       else if targetPlatform.isAvr then "avr"
       else if targetPlatform.isAlpha then "alpha"
-      else throw "unknown emulation for platform: " + targetPlatform.config;
+      else throw "unknown emulation for platform: ${targetPlatform.config}";
     in targetPlatform.platform.bfdEmulation or (fmt + sep + arch);
 
   strictDeps = true;