diff --git a/jemalloc/doc/jemalloc.3.in b/jemalloc/doc/jemalloc.3.in
index f32c4bff..2ac093a6 100644
--- a/jemalloc/doc/jemalloc.3.in
+++ b/jemalloc/doc/jemalloc.3.in
@@ -526,9 +526,13 @@ will disable dirty page purging.
 @roff_prof@is controlled by the
 @roff_prof@JEMALLOC_PROF_PREFIX
 @roff_prof@environment variable.
-@roff_prof@The default average interval is 1 GiB;
-@roff_prof@.Ev JEMALLOC_OPTIONS=31i
-@roff_prof@will disable interval-triggered profile dumping.
+@roff_prof@By default, interval-triggered profile dumping is disabled.
+@roff_prof@This is internally encoded as (1 << -1), and each
+@roff_prof@.Dq I
+@roff_prof@that is specified increments the shift amount.
+@roff_prof@Therefore, e.g.
+@roff_prof@.Ev JEMALLOC_OPTIONS=31I
+@roff_prof@specifies a dump interval of 1 GiB.
 @roff_fill@.It J
 @roff_fill@Each byte of new memory allocated by
 @roff_fill@.Fn @jemalloc_prefix@malloc
diff --git a/jemalloc/include/jemalloc/internal/prof.h b/jemalloc/include/jemalloc/internal/prof.h
index fb55fb90..2c195f39 100644
--- a/jemalloc/include/jemalloc/internal/prof.h
+++ b/jemalloc/include/jemalloc/internal/prof.h
@@ -11,7 +11,7 @@ typedef struct prof_s prof_t;
 /* Option defaults. */
 #define	LG_PROF_BT_MAX_DEFAULT		2
 #define	LG_PROF_SAMPLE_DEFAULT		0
-#define	LG_PROF_INTERVAL_DEFAULT	30
+#define	LG_PROF_INTERVAL_DEFAULT	-1
 
 /*
  * Hard limit on stack backtrace depth.  Note that the version of