diff --git a/CHANGES b/CHANGES
index cf4c82aa5f..8d19b23b12 100644
--- a/CHANGES
+++ b/CHANGES
@@ -1,3 +1,6 @@
+  96.   [cleanup]       <isc/mutex.h> does not need <isc/lang.h> or
+                        <isc/result.h>.
+
   95.   [cleanup]       <isc/mutexblock.h> does not need <isc/result.h>.
 
   94.   [cleanup]       Some installed header files did not compile as C++.
diff --git a/lib/isc/heap.c b/lib/isc/heap.c
index 998cab4d14..51deb0ef7e 100644
--- a/lib/isc/heap.c
+++ b/lib/isc/heap.c
@@ -33,6 +33,7 @@
 #include <isc/assertions.h>
 #include <isc/heap.h>
 #include <isc/mem.h>
+#include <isc/result.h>
 
 /*
  * Note: to make heap_parent and heap_left easy to compute, the first
diff --git a/lib/isc/include/isc/mutexblock.h b/lib/isc/include/isc/mutexblock.h
index 04499fb556..91c090cd2b 100644
--- a/lib/isc/include/isc/mutexblock.h
+++ b/lib/isc/include/isc/mutexblock.h
@@ -20,6 +20,7 @@
 
 #include <isc/lang.h>
 #include <isc/mutex.h>
+#include <isc/types.h>
 
 ISC_LANG_BEGINDECLS
 
diff --git a/lib/isc/mem.c b/lib/isc/mem.c
index b612bf822d..19c36bd417 100644
--- a/lib/isc/mem.c
+++ b/lib/isc/mem.c
@@ -28,6 +28,7 @@
 #include <isc/error.h>
 #include <isc/mem.h>
 #include <isc/ondestroy.h>
+#include <isc/result.h>
 
 #ifndef ISC_SINGLETHREADED
 #include <isc/mutex.h>
diff --git a/lib/isc/mutexblock.c b/lib/isc/mutexblock.c
index 4f8d11bfcc..a84c7e42aa 100644
--- a/lib/isc/mutexblock.c
+++ b/lib/isc/mutexblock.c
@@ -19,6 +19,7 @@
 
 #include <isc/mutex.h>
 #include <isc/mutexblock.h>
+#include <isc/result.h>
 
 isc_result_t
 isc_mutexblock_init(isc_mutex_t *block, unsigned int count) {
diff --git a/lib/isc/pthreads/include/isc/mutex.h b/lib/isc/pthreads/include/isc/mutex.h
index c0d5a88159..962c19e081 100644
--- a/lib/isc/pthreads/include/isc/mutex.h
+++ b/lib/isc/pthreads/include/isc/mutex.h
@@ -20,11 +20,6 @@
 
 #include <pthread.h>
 
-#include <isc/lang.h>
-#include <isc/result.h>
-
-ISC_LANG_BEGINDECLS
-
 typedef pthread_mutex_t	isc_mutex_t;
 
 /* XXX We could do fancier error handling... */
@@ -45,6 +40,4 @@ typedef pthread_mutex_t	isc_mutex_t;
 	((pthread_mutex_destroy((mp)) == 0) ? \
 	 ISC_R_SUCCESS : ISC_R_UNEXPECTED)
 
-ISC_LANG_ENDDECLS
-
 #endif /* ISC_MUTEX_H */