diff --git a/changes/read_circpriorityhalflife_correctly b/changes/read_circpriorityhalflife_correctly
index 9fcbd6923e6dbb14acf9aed6cc328aafef686dcb..651e4db2848d619def526dbd2b112dca10ca14ec 100644
--- a/changes/read_circpriorityhalflife_correctly
+++ b/changes/read_circpriorityhalflife_correctly
@@ -2,4 +2,6 @@
    - Fix a stupid parenthesization error that made every possible value
      of CircPriorityHalflifeMsec get treated as "1 msec".  Bugfix on
      0.2.2.7-alpha.
-
+   - Rename CircPriorityHalflifeMsec to CircuitPriorityHalflifeMsec,
+     so authorities can tell newer relays about the option without
+     breaking older ones.
diff --git a/doc/spec/dir-spec.txt b/doc/spec/dir-spec.txt
index cfe6cd8f9295200920d5edcb0bfc1e9f624b8fe5..b88e838f3696cc4a8d582dc7541adf92330d43a2 100644
--- a/doc/spec/dir-spec.txt
+++ b/doc/spec/dir-spec.txt
@@ -1149,9 +1149,11 @@
         transit in the network at any given time. Obeyed by Tor 0.2.1.20
         and later.
 
-        "CircPriorityHalflifeMsec" -- the halflife parameter used when
+        "CircuitPriorityHalflifeMsec" -- the halflife parameter used when
         weighting which circuit will send the next cell. Obeyed by Tor
-        0.2.2.7-alpha and later.
+        0.2.2.10-alpha and later.  (Versions of Tor between 0.2.2.7-alpha
+        and 0.2.2.10-alpha recognized a "CircPriorityHalflifeMsec" parameter,
+        but mishandled it badly.)
 
    The authority section of a vote contains the following items, followed
    in turn by the authority's current key certificate:
diff --git a/src/or/relay.c b/src/or/relay.c
index c417cbedcb589900d660298be5955f3c82465c2d..fab2d8896e5bae88c91ae522d5b31fafe36e6d30 100644
--- a/src/or/relay.c
+++ b/src/or/relay.c
@@ -1865,9 +1865,9 @@ cell_ewma_set_scale_factor(or_options_t *options, networkstatus_t *consensus)
     source = "CircuitPriorityHalflife in configuration";
   } else if (consensus &&
              (halflife_ms = networkstatus_get_param(
-                   consensus, "CircPriorityHalflifeMsec", -1)) >= 0) {
+                   consensus, "CircuitPriorityHalflifeMsec", -1)) >= 0) {
     halflife = ((double)halflife_ms)/1000.0;
-    source = "CircPriorityHalflifeMsec in consensus";
+    source = "CircuitPriorityHalflifeMsec in consensus";
   } else {
     halflife = EWMA_DEFAULT_HALFLIFE;
     source = "Default value";