diff --git a/cddl/contrib/opensolaris/cmd/dtrace/test/tst/common/java_api/tst.FunctionLookup.c b/cddl/contrib/opensolaris/cmd/dtrace/test/tst/common/java_api/tst.FunctionLookup.c
--- a/cddl/contrib/opensolaris/cmd/dtrace/test/tst/common/java_api/tst.FunctionLookup.c
+++ b/cddl/contrib/opensolaris/cmd/dtrace/test/tst/common/java_api/tst.FunctionLookup.c
@@ -41,7 +41,7 @@
 }
 
 int
-main()
+main(void)
 {
 	f2(f1, 3);
 
diff --git a/cddl/contrib/opensolaris/cmd/dtrace/test/tst/common/java_api/tst.ProbeData.c b/cddl/contrib/opensolaris/cmd/dtrace/test/tst/common/java_api/tst.ProbeData.c
--- a/cddl/contrib/opensolaris/cmd/dtrace/test/tst/common/java_api/tst.ProbeData.c
+++ b/cddl/contrib/opensolaris/cmd/dtrace/test/tst/common/java_api/tst.ProbeData.c
@@ -66,7 +66,7 @@
 }
 
 int
-main()
+main(void)
 {
 	/*
 	 * Avoid length of 1, 2, 4, or 8 bytes so DTrace will treat the data as
diff --git a/cddl/contrib/opensolaris/cmd/dtrace/test/tst/common/pid/tst.weak1.c b/cddl/contrib/opensolaris/cmd/dtrace/test/tst/common/pid/tst.weak1.c
--- a/cddl/contrib/opensolaris/cmd/dtrace/test/tst/common/pid/tst.weak1.c
+++ b/cddl/contrib/opensolaris/cmd/dtrace/test/tst/common/pid/tst.weak1.c
@@ -33,8 +33,7 @@
  * leading underscores.
  */
 
-#pragma weak _go = go
-
+extern int _go(int);
 int go(int);
 
 int
@@ -57,3 +56,5 @@
 	for (;;)
 		getpid();
 }
+
+#pragma weak _go = go
diff --git a/cddl/contrib/opensolaris/cmd/dtrace/test/tst/common/pid/tst.weak2.c b/cddl/contrib/opensolaris/cmd/dtrace/test/tst/common/pid/tst.weak2.c
--- a/cddl/contrib/opensolaris/cmd/dtrace/test/tst/common/pid/tst.weak2.c
+++ b/cddl/contrib/opensolaris/cmd/dtrace/test/tst/common/pid/tst.weak2.c
@@ -33,14 +33,14 @@
  * leading underscores.
  */
 
+extern int _go(int);
+
 static int __unused
 go(int a)
 {
 	return (a + 1);
 }
 
-#pragma weak _go = go
-
 static void
 handle(int sig __unused)
 {
@@ -55,3 +55,5 @@
 	for (;;)
 		getpid();
 }
+
+#pragma weak _go = go