diff --git a/ChangeLog b/ChangeLog
index a9929f82..b7381a58 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -13,6 +13,8 @@ brevity.  Much more detail can be found in the git revision history:
     when resizing from/to a size class that is not a multiple of the chunk size.
   - Fix prof_tctx_dump_iter() to filter out nodes that were created after heap
     profile dumping started.
+  - Work around a potentially bad thread-specific data initialization
+    interaction with NPTL (glibc's pthreads implementation).
 
 * 4.0.2 (September 21, 2015)
 
diff --git a/src/tsd.c b/src/tsd.c
index 2100833a..9ffe9afe 100644
--- a/src/tsd.c
+++ b/src/tsd.c
@@ -73,6 +73,9 @@ tsd_cleanup(void *arg)
 	tsd_t *tsd = (tsd_t *)arg;
 
 	switch (tsd->state) {
+	case tsd_state_uninitialized:
+		/* Do nothing. */
+		break;
 	case tsd_state_nominal:
 #define O(n, t)								\
 		n##_cleanup(tsd);