diff --git a/pkgs/development/tools/clang-tools/wrapper b/pkgs/development/tools/clang-tools/wrapper
index fe17880b07d8..53c99a67f2d3 100644
--- a/pkgs/development/tools/clang-tools/wrapper
+++ b/pkgs/development/tools/clang-tools/wrapper
@@ -6,7 +6,7 @@ buildcpath() {
     case $1 in
         -isystem)
             shift
-            path=$path${path':'}$1
+            path=$path${path:+':'}$1
     esac
     shift
   done