diff --git a/CHANGELOG.md b/CHANGELOG.md
index 94dad778..f1cc142e 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -17,6 +17,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 - Drop support for busybox 1.1.3 and similar versions as it can not redefine builtin commands.
 - Drop support for ash 0.3.8 and similar versions as it can not use retrun in sourced script.
+- Remove `call`/`invoke` `<STRING>` syntax.
 
 ## [0.18.0] - 2019-07-09
 
diff --git a/docs/references.md b/docs/references.md
index 7de657b2..5eaa4458 100644
--- a/docs/references.md
+++ b/docs/references.md
@@ -33,14 +33,12 @@ You can write structured *Example* by below DSL.
 
 The line start with `When` is the evaluation. The evaluation type follows after `When`.
 
-| evaluation type                    | Description                                          |
-| :--------------------------------- | :--------------------------------------------------- |
-| call `<FUNCTION> [ARGUMENTS...]`   | Call shell function or external command.             |
-| call `<STRING> [ARGUMENTS...]`     | Eval string and execute.                             |
-| invoke `<FUNCTION> [ARGUMENTS...]` | Call shell function or external command in subshell. |
-| invoke `<STRING> [ARGUMENTS...]`   | Eval string and execute in subshell.                 |
-| run `<FUNCTION> [ARGUMENTS...]`    | Run external command.                                |
-| execute `<SCRIPT> [ARGUMENTS...]`  | Execute shell script file.                           |
+| evaluation type                             | Description                                          |
+| :------------------------------------------ | :--------------------------------------------------- |
+| call `<FUNCTION | COMMAND> [ARGUMENTS...]`  | Call shell function or external command.             |
+| invoke `<FUNCTION| COMMAND> [ARGUMENTS...]` | Call shell function or external command in subshell. |
+| run `<COMMAND> [ARGUMENTS...]`              | Run external command.                                |
+| execute `<SCRIPT> [ARGUMENTS...]`           | Execute shell script file.                           |
 
 Normally you will use `call`. `invoke` is similar to `call` but execute in subshell.
 `invoke` usefull for *override function in evaluation only* and trap `exit`.
diff --git a/lib/core/evaluation.sh b/lib/core/evaluation.sh
index 00a709fa..0c388303 100644
--- a/lib/core/evaluation.sh
+++ b/lib/core/evaluation.sh
@@ -12,11 +12,6 @@ shellspec_syntax 'shellspec_evaluation_execute'
 shellspec_proxy 'shellspec_evaluation' 'shellspec_syntax_dispatch evaluation'
 
 shellspec_evaluation_call() {
-  if ! shellspec_is funcname "$1"; then
-    eval "shellspec_evaluation_eval() { $1; }"
-    shift
-    eval set -- shellspec_evaluation_eval ${1+'"$@"'}
-  fi
   if [ "${SHELLSPEC_DATA:-}" ]; then
     set -- shellspec_evaluation_with_data "$@"
   fi
@@ -38,11 +33,6 @@ shellspec_evaluation_run() {
 shellspec_around_invoke() { "$@"; }
 
 shellspec_evaluation_invoke() {
-  if ! shellspec_is funcname "$1"; then
-    eval "shellspec_evaluation_eval() { $1; }"
-    shift
-    eval set -- shellspec_evaluation_eval ${1+'"$@"'}
-  fi
   if [ "${SHELLSPEC_DATA:-}" ]; then
     set -- shellspec_evaluation_with_data "$@"
   fi
diff --git a/spec/core/evaluation_spec.sh b/spec/core/evaluation_spec.sh
index 96035a78..d4af66cf 100644
--- a/spec/core/evaluation_spec.sh
+++ b/spec/core/evaluation_spec.sh
@@ -37,11 +37,6 @@ Describe "core/evaluation.sh"
       The stdout should equal 'cleanup: 123'
     End
 
-    It 'accepts evaluatable string'
-      When call 'echo "$@"' 1 2 3
-      The stdout should equal '1 2 3'
-    End
-
     It 'ensures errno 0 before evaluating function'
       relay_errno() { return ${?}; }
       When call relay_errno
@@ -118,11 +113,6 @@ Describe "core/evaluation.sh"
       The stdout should equal 'cleanup: 123'
     End
 
-    It 'accepts evaluatable string'
-      When invoke 'echo "$@"' 1 2 3
-      The stdout should equal '1 2 3'
-    End
-
     It 'ensures errno 0 before calling external command'
       shellspec_around_invoke() { "$@"; }
       relay_errno() { return ${?}; }