diff --git a/ext/interbase/config.w32 b/ext/interbase/config.w32
index 78a442d8ca5..55121254630 100644
--- a/ext/interbase/config.w32
+++ b/ext/interbase/config.w32
@@ -5,7 +5,8 @@ ARG_WITH("interbase", "InterBase support", "no");
 
 if (PHP_INTERBASE != "no") {
 
-	if (CHECK_HEADER_ADD_INCLUDE("ibase.h", "CFLAGS_INTERBASE", PHP_PHP_BUILD + "\\interbase\\include;" + PHP_INTERBASE) &&
+	if (CHECK_HEADER_ADD_INCLUDE("ibase.h", "CFLAGS_INTERBASE", 
+				PHP_PHP_BUILD + "\\include\\interbase;" + PHP_PHP_BUILD + "\\interbase\\include;" + PHP_INTERBASE) &&
 			(CHECK_LIB("fbclient_ms.lib", "interbase", PHP_PHP_BUILD + "\\interbase\\lib_ms;" + PHP_INTERBASE) ||
 			 CHECK_LIB("gds32_ms.lib", "interbase", PHP_PHP_BUILD + "\\interbase\\lib_ms;" + PHP_INTERBASE))) {
 
diff --git a/ext/pdo_firebird/config.w32 b/ext/pdo_firebird/config.w32
index b28a89e2eac..9cf5ac1337d 100644
--- a/ext/pdo_firebird/config.w32
+++ b/ext/pdo_firebird/config.w32
@@ -7,7 +7,9 @@ if (PHP_PDO_FIREBIRD != "no") {
 
 	if ((CHECK_LIB("fbclient_ms.lib", "pdo_firebird", PHP_PHP_BUILD + "\\interbase\\lib_ms;" + PHP_PDO_FIREBIRD)
 			|| CHECK_LIB("gds32_ms.lib", "pdo_firebird", PHP_PHP_BUILD + "\\interbase\\lib_ms;" + PHP_PDO_FIREBIRD)
-		) && CHECK_HEADER_ADD_INCLUDE("ibase.h", "CFLAGS_PDO_FIREBIRD", PHP_PHP_BUILD + "\\interbase\\include;" + PHP_PDO_FIREBIRD)) {
+		) && CHECK_HEADER_ADD_INCLUDE("ibase.h", "CFLAGS_PDO_FIREBIRD", 
+				PHP_PHP_BUILD + "\\include\\interbase;" + PHP_PHP_BUILD + "\\interbase\\include;" + PHP_PDO_FIREBIRD)
+		) {
 
 		EXTENSION("pdo_firebird", "pdo_firebird.c firebird_driver.c firebird_statement.c");
 	} else {