diff --git a/examples/gf_example_5.c b/examples/gf_example_5.c
index 8e7dd4e..da6e9ca 100644
--- a/examples/gf_example_5.c
+++ b/examples/gf_example_5.c
@@ -74,4 +74,5 @@ int main(int argc, char **argv)
            gf.extract_word.w32(&gf, a, 30*2, i+15),
            gf.extract_word.w32(&gf, b, 30*2, i+15));
   }
+  return 0;
 }
diff --git a/examples/gf_example_6.c b/examples/gf_example_6.c
index 54cdf83..800a35f 100644
--- a/examples/gf_example_6.c
+++ b/examples/gf_example_6.c
@@ -80,4 +80,5 @@ int main(int argc, char **argv)
            gf.extract_word.w32(&gf, a, 30*4, i+15),
            gf.extract_word.w32(&gf, b, 30*4, i+15));
   }
+  return 0;
 }
diff --git a/examples/gf_example_7.c b/examples/gf_example_7.c
index cd5c44b..ee07d53 100644
--- a/examples/gf_example_7.c
+++ b/examples/gf_example_7.c
@@ -71,4 +71,5 @@ int main(int argc, char **argv)
            gf.extract_word.w32(&gf, a, 3, i),
            gf.extract_word.w32(&gf, b, 3, i));
   }
+  return 0;
 }
diff --git a/test/gf_unit.c b/test/gf_unit.c
index 3384d8e..deaaced 100644
--- a/test/gf_unit.c
+++ b/test/gf_unit.c
@@ -422,4 +422,5 @@ int main(int argc, char **argv)
       gf_general_do_region_check(&gf, a, rc+s_start, rd+d_start, target+d_start, bytes, xor);
     }
   }
+  return 0;
 }
diff --git a/tools/gf_inline_time.c b/tools/gf_inline_time.c
index 193c004..c81e8a9 100644
--- a/tools/gf_inline_time.c
+++ b/tools/gf_inline_time.c
@@ -164,4 +164,5 @@ int main(int argc, char **argv)
     printf("Inline mult:   %10.6lf s   Mops: %10.3lf    %10.3lf Mega-ops/s\n",
            elapsed, dnum/1024.0/1024.0, dnum/1024.0/1024.0/elapsed);
   }
+  return 0;
 }
diff --git a/tools/gf_poly.c b/tools/gf_poly.c
index 8bfedb0..44a24ac 100644
--- a/tools/gf_poly.c
+++ b/tools/gf_poly.c
@@ -179,7 +179,7 @@ void x_to_q_to_i_minus_x(gf_t *gf, int w, int n, gf_general_t *poly, int logq, i
   free(x_to_q);
 }
 
-main(int argc, char **argv)
+int main(int argc, char **argv)
 {
   int w, i, power, n, ap, success;
   gf_t gf;