diff --git a/m4/lx_check_soplex.m4 b/m4/lx_check_soplex.m4
--- a/m4/lx_check_soplex.m4
+++ b/m4/lx_check_soplex.m4
@@ -40,7 +40,7 @@
     lx_soplex_test_prog='
       #include <soplex/soplex.h>
 
-      int main(int argc, char* argv[])
+      int main(int argc, char** argv)
       {
         soplex::SoPlex soplex;
         return 0;