diff --git a/ChangeLog.adoc b/ChangeLog.adoc
index ecfb8cd65..1bae173e6 100644
--- a/ChangeLog.adoc
+++ b/ChangeLog.adoc
@@ -20,6 +20,7 @@ https://weechat.org/files/releasenotes/ReleaseNotes-devel.html[release notes]
 
 Bug fixes::
 
+  * core: fix buffer overflow in function eval_string_base_encode
   * core: fix integer overflow in function util_version_number
   * core: fix integer overflow in base32 encoding/decoding
   * core: fix integer overflow with decimal numbers in calculation of expression
diff --git a/src/core/wee-eval.c b/src/core/wee-eval.c
index e0b981619..c463baaac 100644
--- a/src/core/wee-eval.c
+++ b/src/core/wee-eval.c
@@ -906,7 +906,7 @@ eval_string_base_encode (const char *text)
 
     ptr_string++;
     length = strlen (ptr_string);
-    result = malloc ((length * 4) + 1);
+    result = malloc ((length * 4) + 8 + 1);
     if (!result)
         goto end;