--- a/src/java.desktop/unix/native/libawt_headless/awt/HeadlessToolkit.c	Fri Mar 02 19:10:12 2018 +0100
+++ b/src/java.desktop/unix/native/libawt_headless/awt/HeadlessToolkit.c	Sat Mar 03 08:21:47 2018 +0100
@@ -39,7 +39,7 @@
 
 #ifndef STATIC_BUILD
 // The same function exists in libawt.a::awt_LoadLibrary.c
-JNIEXPORT jboolean JNICALL AWTIsHeadless() {
+JNIEXPORT jboolean JNICALL AWTIsHeadless(void) {
     return JNI_TRUE;
 }
 #endif