diff --git a/CHANGES b/CHANGES
index ef0d344646..7bfe2ae842 100644
--- a/CHANGES
+++ b/CHANGES
@@ -1,3 +1,6 @@
+ 131.   [cleanup]       <isc/mutex.h> and <isc/util.h> need <isc/result.h>
+                        for ISC_R_* codes used in macros.
+
  130.   [cleanup]       <isc/condition.h> does not need <pthread.h> or
                         <isc/boolean.h>, and now includes <isc/types.h>
                         instead of <isc/time.h>.
diff --git a/lib/isc/include/isc/util.h b/lib/isc/include/isc/util.h
index 1d9ff34b35..c429ee0354 100644
--- a/lib/isc/include/isc/util.h
+++ b/lib/isc/include/isc/util.h
@@ -62,6 +62,8 @@
 #define ISC_UTIL_TRACE(a)
 #endif
 
+#include <isc/result.h>		/* for ISC_R_SUCCESS */
+
 #define LOCK(lp) do { \
 	ISC_UTIL_TRACE(fprintf(stderr, "LOCKING %p %s %d\n", (lp), __FILE__, __LINE__)); \
 	RUNTIME_CHECK(isc_mutex_lock((lp)) == ISC_R_SUCCESS); \
diff --git a/lib/isc/pthreads/include/isc/mutex.h b/lib/isc/pthreads/include/isc/mutex.h
index 962c19e081..832a547fb9 100644
--- a/lib/isc/pthreads/include/isc/mutex.h
+++ b/lib/isc/pthreads/include/isc/mutex.h
@@ -20,6 +20,8 @@
 
 #include <pthread.h>
 
+#include <isc/result.h>		/* for ISC_R_ codes */
+
 typedef pthread_mutex_t	isc_mutex_t;
 
 /* XXX We could do fancier error handling... */