diff --git a/Misc/NEWS b/Misc/NEWS
index 87a89fb..a9c9695 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -10,6 +10,8 @@
 Core and Builtins
 -----------------
 
+- Issue #15761: Fix crash when PYTHONEXECUTABLE is set on Mac OS X.
+
 - Issue #15726: Fix incorrect bounds checking in PyState_FindModule.
   Patch by Robin Schreiber.
 
diff --git a/Modules/main.c b/Modules/main.c
index 5b4a7e2..5d1d896 100644
--- a/Modules/main.c
+++ b/Modules/main.c
@@ -616,7 +616,7 @@
        script. */
     if ((p = Py_GETENV("PYTHONEXECUTABLE")) && *p != '\0') {
         wchar_t* buffer;
-        size_t len = strlen(p);
+        size_t len = strlen(p) + 1;
         size_t r;
 
         buffer = malloc(len * sizeof(wchar_t));