diff --git a/configure.ac b/configure.ac
index 639258b..b441910 100644
--- a/configure.ac
+++ b/configure.ac
@@ -451,8 +451,8 @@ AC_CHECK_HEADERS(limits.h sys/types.h sys/stat.h dirent.h)
 AC_CHECK_HEADERS([windows.h], [HAVE_WINDOWS_H=1])
 AC_CHECK_HEADERS([sys/wait.h], [HAVE_SYS_WAIT_H=1])
 
-AC_CHECK_HEADERS([stdint.h], [PCRE2_HAVE_STDINT_H=1])
-AC_CHECK_HEADERS([inttypes.h], [PCRE2_HAVE_INTTYPES_H=1])
+AC_CHECK_HEADERS([stdint.h], [PCRE2_HAVE_STDINT_H=1], [PCRE2_HAVE_STDINT_H=0])
+AC_CHECK_HEADERS([inttypes.h], [PCRE2_HAVE_INTTYPES_H=1], [PCRE2_HAVE_INTTYPES_H=0])
 AC_SUBST([PCRE2_HAVE_STDINT_H])
 AC_SUBST([PCRE2_HAVE_INTTYPES_H])