diff --git a/m4/lx_check_cplex.m4 b/m4/lx_check_cplex.m4
--- a/m4/lx_check_cplex.m4
+++ b/m4/lx_check_cplex.m4
@@ -46,7 +46,7 @@
       #include <ilcplex/cplex.h>
       }
 
-      int main(int argc, char* argv[])
+      int main(int argc, char** argv)
       {
         CPXENVptr env = NULL;
         return 0;
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();
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;