diff --git a/ChangeLog b/ChangeLog
index fa4e707bab..0f71d41b0a 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+2018-03-09  Florian Weimer  <fweimer@redhat.com>
+
+	* malloc/malloc.c (prev_size, set_prev_size, prev_chunk): Fix typo
+	in comment.
+
 2018-03-09  Aurelien Jarno  <aurelien@aurel32.net>
 
 	[BZ #22919]
diff --git a/malloc/malloc.c b/malloc/malloc.c
index 58f9acd4d1..e229181c5e 100644
--- a/malloc/malloc.c
+++ b/malloc/malloc.c
@@ -1287,13 +1287,13 @@ nextchunk-> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 /* Ptr to next physical malloc_chunk. */
 #define next_chunk(p) ((mchunkptr) (((char *) (p)) + chunksize (p)))
 
-/* Size of the chunk below P.  Only valid if prev_inuse (P).  */
+/* Size of the chunk below P.  Only valid if !prev_inuse (P).  */
 #define prev_size(p) ((p)->mchunk_prev_size)
 
-/* Set the size of the chunk below P.  Only valid if prev_inuse (P).  */
+/* Set the size of the chunk below P.  Only valid if !prev_inuse (P).  */
 #define set_prev_size(p, sz) ((p)->mchunk_prev_size = (sz))
 
-/* Ptr to previous physical malloc_chunk.  Only valid if prev_inuse (P).  */
+/* Ptr to previous physical malloc_chunk.  Only valid if !prev_inuse (P).  */
 #define prev_chunk(p) ((mchunkptr) (((char *) (p)) - prev_size (p)))
 
 /* Treat space at ptr + offset as a chunk */