diff --git a/Shorewall/Perl/Shorewall/Compiler.pm b/Shorewall/Perl/Shorewall/Compiler.pm
index cdf1c7611..5b587c6d7 100644
--- a/Shorewall/Perl/Shorewall/Compiler.pm
+++ b/Shorewall/Perl/Shorewall/Compiler.pm
@@ -313,9 +313,9 @@ sub generate_script_2() {
 
 	    if ( $global_variables == ( ALL_COMMANDS | NOT_RESTORE ) ) {
 
+		verify_required_interfaces(0);
 		set_global_variables(0, 0);
-
-		handle_optional_interfaces(0);
+		handle_optional_interfaces;
 	    }
 
 	    emit ';;';
@@ -327,19 +327,21 @@ sub generate_script_2() {
 	    push_indent;
 	}
 
+	verify_required_interfaces(1);
 	set_global_variables(1,1);
 
 	if ( $global_variables & NOT_RESTORE ) {
-	    handle_optional_interfaces(1);
+	    handle_optional_interfaces;
 	    emit ';;';
 	    pop_indent;
 	    pop_indent;
 	    emit ( 'esac' );
 	} else {
-	    handle_optional_interfaces(1);
+	    handle_optional_interfaces;
 	}
     } else {
-	emit( 'true' ) unless handle_optional_interfaces(1);
+	verify_required_interfaces(1);
+	emit( 'true' ) unless handle_optional_interfaces;
     }
 
     pop_indent;
diff --git a/Shorewall/Perl/Shorewall/Providers.pm b/Shorewall/Perl/Shorewall/Providers.pm
index 35a1aae12..1c78c918d 100644
--- a/Shorewall/Perl/Shorewall/Providers.pm
+++ b/Shorewall/Perl/Shorewall/Providers.pm
@@ -2195,17 +2195,13 @@ sub provider_realm( $ ) {
 }
 
 #
-# This function is called by the compiler when it is generating the detect_configuration() function.
-# The function calls Shorewall::Zones::verify_required_interfaces then emits code to set the
-# ..._IS_USABLE interface variables appropriately for the  optional interfaces
+# Perform processing related to optional interfaces. Returns true if there are optional interfaces.
+
 #
-# Returns true if there were required or optional interfaces
-#
-sub handle_optional_interfaces( $ ) {
+sub handle_optional_interfaces() {
 
     my @interfaces;
     my $wildcards;
-
     #
     # First do the provider interfacess. Those that are real providers will never have wildcard physical
     # names but they might derive from wildcard interface entries. Optional interfaces which do not have
@@ -2229,10 +2225,6 @@ sub handle_optional_interfaces( $ ) {
 
     if ( @interfaces ) {
 	my $require     = $config{REQUIRE_INTERFACE};
-	my $gencase     = shift;
-
-	verify_required_interfaces( $gencase );
-	emit '' if $gencase;
 
 	emit( 'HAVE_INTERFACE=', '' ) if $require;
 	#
@@ -2396,8 +2388,6 @@ sub handle_optional_interfaces( $ ) {
 
 	return 1;
     }
-
-    verify_required_interfaces( shift );
 }
 
 #
diff --git a/Shorewall/Perl/Shorewall/Zones.pm b/Shorewall/Perl/Shorewall/Zones.pm
index 44bd46f2a..fde6876f1 100644
--- a/Shorewall/Perl/Shorewall/Zones.pm
+++ b/Shorewall/Perl/Shorewall/Zones.pm
@@ -2021,6 +2021,7 @@ sub verify_required_interfaces( $ ) {
 
 	emit( "esac\n" );
 
+	$returnvalue = 1;
     }
 
     $interfaces = find_interfaces_by_option( 'required' );
@@ -2066,7 +2067,7 @@ sub verify_required_interfaces( $ ) {
 	    emit( ';;' );
 	    pop_indent;
 	    pop_indent;
-	    emit( 'esac' );
+	    emit( "esac\n" );
 	}
 
 	$returnvalue = 1;