diff --git a/configure.ac b/configure.ac
index 4bb1c29..9969829 100644
--- a/configure.ac
+++ b/configure.ac
@@ -17,7 +17,7 @@ AC_LANG_C
 AC_PROG_CC
 AC_PROG_MAKE_SET
 
-AC_PATH_PROG(PKG_CONFIG, pkg-config)
+AC_PATH_PROG(PKG_CONFIG, pkg-config, [AC_MSG_ERROR([pkg-config not found.])])
 
 # Checks for header files.
 AC_HEADER_STDC