diff --git a/pkgs/build-support/cc-wrapper/cc-wrapper.sh b/pkgs/build-support/cc-wrapper/cc-wrapper.sh
index 1b43d7cc211a..8003fe1d8f38 100644
--- a/pkgs/build-support/cc-wrapper/cc-wrapper.sh
+++ b/pkgs/build-support/cc-wrapper/cc-wrapper.sh
@@ -126,7 +126,7 @@ fi
 
 if [[ "$isCpp" = 1 ]]; then
     if [[ "$cppInclude" = 1 ]]; then
-        NIX_@infixSalt@_CFLAGS_COMPILE+=" ${NIX_@infixSalt@_CXXSTDLIB_COMPILE-@default_cxx_stdlib_compile@}"
+        NIX_@infixSalt@_CFLAGS_COMPILE+=" ${NIX_@infixSalt@_CXXSTDLIB_COMPILE:-@default_cxx_stdlib_compile@}"
     fi
     NIX_@infixSalt@_CFLAGS_LINK+=" $NIX_@infixSalt@_CXXSTDLIB_LINK"
 fi