--- ./caretx.c.orig	2018-05-21 12:29:23.000000000 +0000
+++ ./caretx.c	2018-09-28 14:05:46.785353073 +0000
@@ -56,7 +56,8 @@ Perl_set_caret_X(pTHX) {
     SV *const caret_x = GvSV(tmpgv);
 #if defined(OS2)
     sv_setpv(caret_x, os2_execname(aTHX));
-#elif defined(USE_KERN_PROC_PATHNAME)
+#else
+#  ifdef USE_KERN_PROC_PATHNAME
     size_t size = 0;
     int mib[4];
     mib[0] = CTL_KERN;
@@ -76,7 +77,7 @@ Perl_set_caret_X(pTHX) {
             return;
         }
     }
-#elif defined(USE_NSGETEXECUTABLEPATH)
+#  elif defined(USE_NSGETEXECUTABLEPATH)
     char buf[1];
     uint32_t size = sizeof(buf);
 
@@ -95,7 +96,7 @@ Perl_set_caret_X(pTHX) {
             return;
         }
     }
-#elif defined(HAS_PROCSELFEXE)
+#  elif defined(HAS_PROCSELFEXE)
     char buf[MAXPATHLEN];
     SSize_t len = readlink(PROCSELFEXE_PATH, buf, sizeof(buf) - 1);
     /* NOTE: if the length returned by readlink() is sizeof(buf) - 1,
@@ -125,7 +126,7 @@ Perl_set_caret_X(pTHX) {
         sv_setpvn(caret_x, buf, len);
         return;
     }
-#elif defined(WIN32)
+#  elif defined(WIN32)
     char *ansi;
     WCHAR widename[MAX_PATH];
     GetModuleFileNameW(NULL, widename, sizeof(widename)/sizeof(WCHAR));
@@ -133,7 +134,7 @@ Perl_set_caret_X(pTHX) {
     sv_setpv(caret_x, ansi);
     win32_free(ansi);
     return;
-#else
+#  endif
     /* Fallback to this:  */
     sv_setpv(caret_x, PL_origargv[0]);
 #endif