diff --git a/m4/lx_check_glpk.m4 b/m4/lx_check_glpk.m4
--- a/m4/lx_check_glpk.m4
+++ b/m4/lx_check_glpk.m4
@@ -42,7 +42,7 @@
       #include <glpk.h>
       }
 
-      int main(int argc, char* argv[])
+      int main(int argc, char** argv)
       {
         LPX *lp;
         lp = lpx_create_prob();