diff --git a/testsuite/lib/libffi.exp b/testsuite/lib/libffi.exp
index 1b8b008f..0d746272 100644
--- a/testsuite/lib/libffi.exp
+++ b/testsuite/lib/libffi.exp
@@ -182,7 +182,7 @@ proc libffi_target_compile { source dest type options } {
     # TOOL_OPTIONS must come first, so that it doesn't override testcase
     # specific options.
     if [info exists TOOL_OPTIONS] {
-	lappend  options [concat "additional_flags=$TOOL_OPTIONS" $options];
+	lappend  options "additional_flags=$TOOL_OPTIONS"
     }
 
     # search for ffi_mips.h in srcdir, too