diff --git a/README.md b/README.md
index 048f3057d..14f1dc515 100644
--- a/README.md
+++ b/README.md
@@ -99,7 +99,7 @@ Procedures for each standard are provided by the following R7RS-style libraries:
 cmake -B build -DCMAKE_BUILD_TYPE=Release
 cd build
 make package
-sudo apt install build/meevax_0.5.1_amd64.deb
+sudo apt install build/meevax_0.5.2_amd64.deb
 ```
 
 or
@@ -131,9 +131,9 @@ sudo rm -rf /usr/local/share/meevax
 
 | Target Name | Description
 |-------------|-------------
-| `all`       | Build shared-library `libmeevax.0.5.1.so` and executable `meevax`
+| `all`       | Build shared-library `libmeevax.0.5.2.so` and executable `meevax`
 | `test`      | Test executable `meevax`
-| `package`   | Generate debian package `meevax_0.5.1_amd64.deb`
+| `package`   | Generate debian package `meevax_0.5.2_amd64.deb`
 | `install`   | Copy files into `/usr/local` directly
 
 ## Usage
@@ -158,7 +158,7 @@ See [LICENSE](./LICENSE).
 ## References
 
 | Authors                                                                                               | Year | Title                                                                                                                                     | Journal Title / Publisher                                                                                                                                 | Pages          |
-|-------------------------------------------------------------------------------------------------------|:----:|-------------------------------------------------------------------------------------------------------------------------------------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------|----------------|
+|-------------------------------------------------------------------------------------------------------|:----:|-------------------------------------------------------------------------------------------------------------------------------------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------|:--------------:|
 | <a id="McCarthy-1960"               ></a> John McCarthy                                               | 1960 | [Recursive functions of symbolic expressions and their computation by machine, Part I](https://dl.acm.org/doi/10.1145/367177.367199)      | [Communications of the ACM, Volume 3, Issue 4](https://dl.acm.org/toc/cacm/1960/3/4)                                                                      | 184&#x2011;195 |
 | <a id="Landin-1964"                 ></a> P. J. Landin                                                | 1964 | [The Mechanical Evaluation of Expressions](https://academic.oup.com/comjnl/article/6/4/308/375725)                                        | [The Computor Journal, Volume 6, Issue 4](https://academic.oup.com/comjnl/issue/6/4)                                                                      | 308&#x2011;320 |
 | <a id="Henderson-1980"              ></a> Peter Henderson                                             | 1980 | [Functional Programming: Application and Implementation](https://archive.org/details/functionalprogra0000hend/mode/2up)                   | Prentice Hall                                                                                                                                             |                |
diff --git a/VERSION b/VERSION
index 4b9fcbec1..cb0c939a9 100644
--- a/VERSION
+++ b/VERSION
@@ -1 +1 @@
-0.5.1
+0.5.2
diff --git a/basis/srfi-45.ss b/basis/srfi-45.ss
index 6e07b5634..5a550fe38 100644
--- a/basis/srfi-45.ss
+++ b/basis/srfi-45.ss
@@ -1,7 +1,10 @@
 (define-library (srfi 45) ; Based on r7rs reference implementation.
-  (import (only (meevax core) define-syntax)
+  (import (only (meevax boolean) not)
+          (only (meevax comparator) eq?)
+          (only (meevax core) define define-syntax if lambda quote)
+          (only (meevax list) list)
           (only (meevax macro-transformer) er-macro-transformer)
-          (scheme r4rs essential))
+          (only (meevax pair) pair? cons car cdr cadr cddr set-car! set-cdr!))
 
   (export delay eager force lazy promise?)
 
@@ -11,8 +14,9 @@
            (cons <promise> (cons done? value)))
 
          (define (promise? x)
-           (and (pair? x)
-                (eq? <promise> (car x))))
+           (if (pair? x)
+               (eq? <promise> (car x))
+               #f))
 
          (define promise-done? cadr)
 
diff --git a/configure/README.md b/configure/README.md
index db3661b97..7f229359f 100644
--- a/configure/README.md
+++ b/configure/README.md
@@ -149,7 +149,7 @@ See [LICENSE](./LICENSE).
 ## References
 
 | Authors                                                                                               | Year | Title                                                                                                                                     | Journal Title / Publisher                                                                                                                                 | Pages          |
-|-------------------------------------------------------------------------------------------------------|:----:|-------------------------------------------------------------------------------------------------------------------------------------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------|----------------|
+|-------------------------------------------------------------------------------------------------------|:----:|-------------------------------------------------------------------------------------------------------------------------------------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------|:--------------:|
 | <a id="McCarthy-1960"               ></a> John McCarthy                                               | 1960 | [Recursive functions of symbolic expressions and their computation by machine, Part I](https://dl.acm.org/doi/10.1145/367177.367199)      | [Communications of the ACM, Volume 3, Issue 4](https://dl.acm.org/toc/cacm/1960/3/4)                                                                      | 184&#x2011;195 |
 | <a id="Landin-1964"                 ></a> P. J. Landin                                                | 1964 | [The Mechanical Evaluation of Expressions](https://academic.oup.com/comjnl/article/6/4/308/375725)                                        | [The Computor Journal, Volume 6, Issue 4](https://academic.oup.com/comjnl/issue/6/4)                                                                      | 308&#x2011;320 |
 | <a id="Henderson-1980"              ></a> Peter Henderson                                             | 1980 | [Functional Programming: Application and Implementation](https://archive.org/details/functionalprogra0000hend/mode/2up)                   | Prentice Hall                                                                                                                                             |                |