diff --git a/configure.ac b/configure.ac
index fcb9ab7315d9d761e0c55ee088be1ac84f509b29..43e916eedace9871837a1c6fde616ca9bbe13734 100644
--- a/configure.ac
+++ b/configure.ac
@@ -465,10 +465,10 @@ if test "$PKGCONFIG" != "no" ; then
   if test "$SSL_EXISTS" -eq "0"; then
     SSL_LIBS=`$PKGCONFIG --libs-only-l openssl 2>/dev/null`
     SSL_LDFLAGS=`$PKGCONFIG --libs-only-L openssl 2>/dev/null`
-    SSL_CFLAGS=`$PKGCONFIG --cflags openssl 2>/dev/null`
+    SSL_CPPFLAGS=`$PKGCONFIG --cflags-only-I openssl 2>/dev/null`
 
     LIBS="$LIBS $SSL_LIBS"
-    CFLAGS="$CFLAGS $SSL_CFLAGS"
+    CPPFLAGS="$CPPFLAGS $SSL_CPPFLAGS"
     LDFLAGS="$LDFLAGS $SSL_LDFLAGS"
 
     AC_MSG_RESULT([yes])