diff --git a/configure.ac b/configure.ac
index 30c6a558..91b3571e 100644
--- a/configure.ac
+++ b/configure.ac
@@ -55,6 +55,7 @@ AM_INIT_AUTOMAKE([subdir-objects dist-lzip])
 
 AC_USE_SYSTEM_EXTENSIONS
 AC_PROG_CC
+AC_PROG_CC_C99
 AM_PROG_CC_C_O
 
 dnl