--- lib/rpmscript.c
+++ lib/rpmscript.c
@@ -390,7 +390,7 @@ rpmRC rpmScriptRun(rpmScript script, int
     if (script == NULL) return RPMRC_OK;
 
     ARGV_t args = NULL;
-    rpmlogLvl lvl = (script->flags & RPMSCRIPT_FLAG_CRITICAL) ?
+    rpmlogLvl lvl = (rpmScriptFlags(script) & RPMSCRIPT_FLAG_CRITICAL) ?
 		    RPMLOG_ERR : RPMLOG_WARNING;
     rpmRC rc;
     int script_type = RPMSCRIPTLET_FORK | RPMSCRIPTLET_EXEC;
@@ -637,5 +637,8 @@ rpmscriptTypes rpmScriptType(rpmScript s
 
 rpmscriptFlags rpmScriptFlags(rpmScript script)
 {
-    return (script != NULL) ? script->flags : 0;
+    rpmscriptFlags flags = (script != NULL) ? script->flags : 0;
+    if (script && script->tag == RPMTAG_POSTIN && rpmExpandNumeric("%{_fail_on_postinstall_errors}"))
+	flags |= RPMSCRIPT_FLAG_CRITICAL;
+    return flags;
 }
--- macros.in
+++ macros.in
@@ -1293,5 +1293,10 @@ end
 %{expand:%__scm_setup_%{__scm} %{!-v:-q}}\
 %{!-N:%autopatch %{-v} %{-p:-p%{-p*}}}
 
+# Should errors in %post scriptlet be propagated as errors?
+#
+# Note: set to 1 for legacy compatibility.
+%_fail_on_postinstall_errors  0
+
 # \endverbatim
 #*/