diff --git a/crypto/bio/bss_file.c b/crypto/bio/bss_file.c
index 826b361fa22322ebaae2257ff0a26431435114c0..a66600c1a34c2ff0812b124da214570080d4cfd9 100644
--- a/crypto/bio/bss_file.c
+++ b/crypto/bio/bss_file.c
@@ -247,7 +247,7 @@ static long MS_CALLBACK file_ctrl(BIO *b, int cmd, long num, void *ptr)
 			ret=0;
 			break;
 			}
-#if defined(OPENSSL_SYS_MSDOS) || defined(OPENSSL_SYS_WINDOWS)
+#if defined(OPENSSL_SYS_MSDOS) || defined(OPENSSL_SYS_WINDOWS) || defined(OPENSSL_SYS_OS2)
 		if (!(num & BIO_FP_TEXT))
 			strcat(p,"b");
 		else