diff --git a/README.md b/README.md
index c2ad3b3..3fff359 100644
--- a/README.md
+++ b/README.md
@@ -54,30 +54,24 @@ this test always fails
 Fail if the given expression evaluates to false.
 
 ***Note:*** *The expression must be a simple command. [Compound
-commands](https://www.gnu.org/software/bash/manual/bash.html#Compound-Commands),
-such as `[[`, can be used only when executed with `bash -c`.
+commands][bash-comp-cmd], such as `[[`, can be used only when executed
+with `bash -c`.
 
 ```bash
 @test 'assert()' {
-  run touch '/var/log/test.log'
+  touch '/var/log/test.log'
   assert [ -e '/var/log/test.log' ]
 }
 ```
 
-On failure, the failed expression, `$status` and `$output` are
-displayed.
+On failure, the failed expression is displayed.
 
 ```
 -- assertion failed --
 expression : [ -e /var/log/test.log ]
-status     : 1
-output     : touch: cannot touch ‘/var/log/test.log’: Permission denied
 --
 ```
 
-If `$output` is longer than one line, it is displayed in *multi-line*
-format.
-
 
 ### `assert_equal`
 
@@ -641,3 +635,4 @@ exclusive. An error is displayed when used simultaneously.
 [bats-core-output]: https://github.com/ztombol/bats-core#output-formatting
 [bats-core]: https://github.com/ztombol/bats-core
 [bats-docs]: https://github.com/ztombol/bats-docs
+[bash-comp-cmd]: https://www.gnu.org/software/bash/manual/bash.html#Compound-Commands
diff --git a/src/assert.bash b/src/assert.bash
index b2d1d2c..7f87dc6 100644
--- a/src/assert.bash
+++ b/src/assert.bash
@@ -49,15 +49,13 @@ fail() {
   return 1
 }
 
-# Fail and display details if the expression evaluates to false. Details
-# include the expression, `$status' and `$output'.
+# Fail and display the expression if it evaluates to false.
 #
 # NOTE: The expression must be a simple command. Compound commands, such
 #       as `[[', can be used only when executed with `bash -c'.
 #
 # Globals:
-#   status
-#   output
+#   none
 # Arguments:
 #   $1 - expression
 # Returns:
@@ -67,18 +65,8 @@ fail() {
 #   STDERR - details, on failure
 assert() {
   if ! "$@"; then
-    { local -ar single=(
-        'expression' "$*"
-        'status'     "$status"
-      )
-      local -ar may_be_multi=(
-        'output'     "$output"
-      )
-      local -ir width="$( batslib_get_max_single_line_key_width \
-                            "${single[@]}" "${may_be_multi[@]}" )"
-      batslib_print_kv_single "$width" "${single[@]}"
-      batslib_print_kv_single_or_multi "$width" "${may_be_multi[@]}"
-    } | batslib_decorate 'assertion failed' \
+    batslib_print_kv_single 10 'expression' "$*" \
+      | batslib_decorate 'assertion failed' \
       | fail
   fi
 }
diff --git a/test/50-assert-11-assert.bats b/test/50-assert-11-assert.bats
index 5ada1c6..6b7606b 100755
--- a/test/50-assert-11-assert.bats
+++ b/test/50-assert-11-assert.bats
@@ -8,30 +8,11 @@ load test_helper
   [ "${#lines[@]}" -eq 0 ]
 }
 
-@test 'assert() <expression>: returns 1 and displays details if <expression> evaluates to FALSE' {
-  run bash -c 'echo "a"
-               false'
+@test 'assert() <expression>: returns 1 and displays <expression> if it evaluates to FALSE' {
   run assert false
   [ "$status" -eq 1 ]
-  [ "${#lines[@]}" -eq 5 ]
+  [ "${#lines[@]}" -eq 3 ]
   [ "${lines[0]}" == '-- assertion failed --' ]
   [ "${lines[1]}" == 'expression : false' ]
-  [ "${lines[2]}" == 'status     : 1' ]
-  [ "${lines[3]}" == 'output     : a' ]
-  [ "${lines[4]}" == '--' ]
-}
-
-@test "assert() <expression>: displays \`\$output' in multi-line format if it is longer than one line" {
-  run bash -c 'printf "a 0\na 1"
-               false'
-  run assert false
-  [ "$status" -eq 1 ]
-  [ "${#lines[@]}" -eq 7 ]
-  [ "${lines[0]}" == '-- assertion failed --' ]
-  [ "${lines[1]}" == 'expression : false' ]
-  [ "${lines[2]}" == 'status     : 1' ]
-  [ "${lines[3]}" == 'output (2 lines):' ]
-  [ "${lines[4]}" == '  a 0' ]
-  [ "${lines[5]}" == '  a 1' ]
-  [ "${lines[6]}" == '--' ]
+  [ "${lines[2]}" == '--' ]
 }