diff --git a/configure.ac b/configure.ac
index 0712d6b46..b7c046f1c 100644
--- a/configure.ac
+++ b/configure.ac
@@ -294,10 +294,12 @@ if test "x$enable_monodoc" = "xyes" -a "x$doc_sources_dir" != "x$prefix/lib/mono
 fi
 echo "---"
 
-mono_prefix=`pkg-config --variable=prefix mono`
-if test "x$mono_prefix" != "x$prefix"; then
-        AC_WARN(Prefix to use ($prefix) is not the same as Mono's ($mono_prefix). Consider using
-		    ./configure --prefix=$mono_prefix
-		    See the README for more information.
-	)
+if test "x$has_mono" = "xtrue"; then
+	mono_prefix=`pkg-config --variable=prefix mono`
+	if test "x$mono_prefix" != "x$prefix"; then
+		AC_MSG_WARN(Prefix to use ($prefix) is not the same as Mono's ($mono_prefix).
+			Consider using ./configure --prefix=$mono_prefix
+			See the README for more information.
+		)
+	fi
 fi