diff --git a/HACKING.md b/HACKING.md
index 71d8a2e..6fd195c 100644
--- a/HACKING.md
+++ b/HACKING.md
@@ -67,6 +67,22 @@ expected_region_highlight=(
 )
 ```
 
+Memos and commas
+----------------
+
+We append to `region_highlight` as follows:
+
+
+```zsh
+region_highlight+=("$start $end $spec, memo=zsh-syntax-highlighting")
+```
+
+That comma is required to cause zsh 5.8 and older to ignore the memo without
+ignoring the `$spec`.  It's a hack, but given that no further 5.8.x patch
+releases are planned, it's been deemed acceptable.  See issue #418 and the
+cross-referenced issues.
+
+
 Miscellany
 ----------
 
diff --git a/changelog.md b/changelog.md
index d68d15c..daeda05 100644
--- a/changelog.md
+++ b/changelog.md
@@ -1,5 +1,23 @@
 # Changes in HEAD
 
+## Notice about an improbable-but-not-impossible forward incompatibility
+
+Everyone can probably skip this section.
+
+The `master` branch of zsh-syntax-highlighting uses a zsh feature that has not
+yet appeared in a zsh release: the `memo=` feature, added to zsh in commit
+zsh-5.8-172-gdd6e702ee (after zsh 5.8, before zsh 5.9).  In the unlikely event
+that this zsh feature should change in an incompatible way before the next
+stable zsh release, set `zsh_highlight__memo_feature=0` in your .zshrc files to
+disable use of the new feature.
+
+z-sy-h dogfoods the new, unreleased zsh feature because that feature was
+added to zsh at z-sy-h's initiative.  The new feature is used in the fix
+to issue #418.
+
+
+## Other changes:
+
 - Document `$ZSH_HIGHLIGHT_MAXLENGTH`.
   [#698]
 
@@ -89,6 +107,12 @@
   The `assign` style remains supported and has precedence.
   [#585]
 
+- Fix interoperability issue with other plugins that use highlighting.  The fix
+  requires zsh 5.8.0.3 or newer.  (zsh 5.8.0.2-dev from the `master` branch,
+  revision zsh-5.8-172-gdd6e702ee or newer is also fine.)
+  [#418, https://github.com/okapia/zsh-viexchange/issues/1]
+
+
 # Changes in version 0.7.1
 
 - Remove out-of-date information from the 0.7.0 changelog.
diff --git a/highlighters/pattern/pattern-highlighter.zsh b/highlighters/pattern/pattern-highlighter.zsh
index 054eff7..e0422d0 100644
--- a/highlighters/pattern/pattern-highlighter.zsh
+++ b/highlighters/pattern/pattern-highlighter.zsh
@@ -54,7 +54,7 @@ _zsh_highlight_pattern_highlighter_loop()
   local -a match mbegin mend
   local MATCH; integer MBEGIN MEND
   if [[ "$buf" == (#b)(*)(${~pat})* ]]; then
-    region_highlight+=("$((mbegin[2] - 1)) $mend[2] $ZSH_HIGHLIGHT_PATTERNS[$pat]")
+    region_highlight+=("$((mbegin[2] - 1)) $mend[2] $ZSH_HIGHLIGHT_PATTERNS[$pat], memo=zsh-syntax-highlighting")
     "$0" "$match[1]" "$pat"; return $?
   fi
 }
diff --git a/highlighters/regexp/regexp-highlighter.zsh b/highlighters/regexp/regexp-highlighter.zsh
index 26f9da3..0d43aac 100644
--- a/highlighters/regexp/regexp-highlighter.zsh
+++ b/highlighters/regexp/regexp-highlighter.zsh
@@ -55,7 +55,7 @@ _zsh_highlight_regexp_highlighter_loop()
   local -a match mbegin mend
   while true; do
     [[ "$buf" =~ "$pat" ]] || return;
-    region_highlight+=("$((MBEGIN - 1 + OFFSET)) $((MEND + OFFSET)) $ZSH_HIGHLIGHT_REGEXP[$pat]")
+    region_highlight+=("$((MBEGIN - 1 + OFFSET)) $((MEND + OFFSET)) $ZSH_HIGHLIGHT_REGEXP[$pat], memo=zsh-syntax-highlighting")
     buf="$buf[$(($MEND+1)),-1]"
     OFFSET=$((MEND+OFFSET));
   done
diff --git a/tests/test-highlighting.zsh b/tests/test-highlighting.zsh
index 0e8e03e..30e93b1 100755
--- a/tests/test-highlighting.zsh
+++ b/tests/test-highlighting.zsh
@@ -190,7 +190,7 @@ run_test_internal() {
     if
       [[ $start != $exp_start ]] ||
       [[ $end != $exp_end ]] ||
-      [[ $highlight_zone[3] != $expected_highlight_zone[3] ]]
+      [[ ${highlight_zone[3]%,} != ${expected_highlight_zone[3]} ]] # remove the comma that's before the memo field
     then
       print -r -- "not ok $i - $desc - expected ($exp_start $exp_end ${(qqq)expected_highlight_zone[3]}), observed ($start $end ${(qqq)highlight_zone[3]}). $todo"
       if [[ -z $todo ]]; then (( ++print_expected_and_actual )); fi
diff --git a/zsh-syntax-highlighting.zsh b/zsh-syntax-highlighting.zsh
index d27d2cb..f98dc4b 100644
--- a/zsh-syntax-highlighting.zsh
+++ b/zsh-syntax-highlighting.zsh
@@ -83,12 +83,63 @@ _zsh_highlight()
     return $ret
   }
 
+  # Probe the memo= feature, once.
+  (( ${+zsh_highlight__memo_feature} )) || {
+    region_highlight+=( " 0 0 fg=red, memo=zsh-syntax-highlighting" )
+    case ${region_highlight[-1]} in
+      ("0 0 fg=red")
+        # zsh 5.8 or earlier
+        integer -gr zsh_highlight__memo_feature=0
+        ;;
+      ("0 0 fg=red memo=zsh-syntax-highlighting")
+        # zsh 5.9 or later
+        integer -gr zsh_highlight__memo_feature=1
+        ;;
+      (" 0 0 fg=red, memo=zsh-syntax-highlighting") ;&
+      (*)
+        # We can get here in two ways:
+        #
+        # 1. When not running as a widget.  In that case, $region_highlight is
+        # not a special variable (= one with custom getter/setter functions
+        # written in C) but an ordinary one, so the third case pattern matches
+        # and we fall through to this block.  (The test suite uses this codepath.)
+        #
+        # 2. When running under a future version of zsh that will have changed
+        # the serialization of $region_highlight elements from their underlying
+        # C structs, so that none of the previous case patterns will match.
+        #
+        # In either case, fall back to a version check.
+        #
+        # The memo= feature was added to zsh in commit zsh-5.8-172-gdd6e702ee.
+        # The version number at the time was 5.8.0.2-dev (see Config/version.mk).
+        # Therefore, on 5.8.0.3 and newer the memo= feature is available.
+        #
+        # On zsh version 5.8.0.2 between the aforementioned commit and the
+        # first Config/version.mk bump after it (which, at the time of writing,
+        # is yet to come), this condition will false negative.
+        if is-at-least 5.8.0.3; then
+          integer -gr zsh_highlight__memo_feature=1
+        else
+          integer -gr zsh_highlight__memo_feature=0
+        fi
+        ;;
+    esac
+    region_highlight[-1]=()
+  }
+
+  # Reset region_highlight to build it from scratch
+  if (( zsh_highlight__memo_feature )); then
+    region_highlight=( "${(@)region_highlight:#*memo=zsh-syntax-highlighting*}" )
+  else
+    # Legacy codepath.  Not very interoperable with other plugins (issue #418).
+    region_highlight=()
+  fi
+
   # Remove all highlighting in isearch, so that only the underlining done by zsh itself remains.
   # For details see FAQ entry 'Why does syntax highlighting not work while searching history?'.
   # This disables highlighting during isearch (for reasons explained in README.md) unless zsh is new enough
   # and doesn't have the pattern matching bug
   if [[ $WIDGET == zle-isearch-update ]] && { $zsh_highlight__pat_static_bug || ! (( $+ISEARCHMATCH_ACTIVE )) }; then
-    region_highlight=()
     return $ret
   fi
 
@@ -124,9 +175,6 @@ _zsh_highlight()
   # Do not highlight if there are pending inputs (copy/paste).
   [[ $PENDING -gt 0 ]] && return $ret
 
-  # Reset region highlight to build it from scratch
-  region_highlight=();
-
   {
     local cache_place
     local -a region_highlight_copy
@@ -245,7 +293,7 @@ _zsh_highlight_apply_zle_highlight() {
   else
     start=$second end=$first
   fi
-  region_highlight+=("$start $end $region")
+  region_highlight+=("$start $end $region, memo=zsh-syntax-highlighting")
 }
 
 
@@ -285,7 +333,7 @@ _zsh_highlight_add_highlight()
   shift 2
   for highlight; do
     if (( $+ZSH_HIGHLIGHT_STYLES[$highlight] )); then
-      region_highlight+=("$start $end $ZSH_HIGHLIGHT_STYLES[$highlight]")
+      region_highlight+=("$start $end $ZSH_HIGHLIGHT_STYLES[$highlight], memo=zsh-syntax-highlighting")
       break
     fi
   done