1 files changed, 1 insertions, 0 deletions
diff --git a/m4/mpc.m4 b/m4/mpc.m4
index a014f01..948f553 100644
--- a/m4/mpc.m4
+++ b/m4/mpc.m4
@@ -39,6 +39,7 @@ AC_DEFUN([MPC_PROG_CC_WARNINGCFLAGS], [
          *) AX_C_CHECK_FLAG(-D_FORTIFY_SOURCE=2,,,$1="$$1 -D_FORTIFY_SOURCE=2",) ;;
       esac
       AX_C_CHECK_FLAG(-g,,,$1="$$1 -g",)
+      AX_C_CHECK_FLAG(-std=c99,,,$1="$$1 -std=c99",)
       AX_C_CHECK_FLAG(-pedantic,,,$1="$$1 -pedantic",)
       AX_C_CHECK_FLAG(-Wno-long-long,,,$1="$$1 -Wno-long-long",)
       AX_C_CHECK_FLAG(-Wall,,,$1="$$1 -Wall",)