diff --git a/Makefile b/Makefile
index ab6f6e14eb..0ab1cff30d 100644
--- a/Makefile
+++ b/Makefile
@@ -702,7 +702,9 @@ ifeq ($(uname_S),SunOS)
 	NO_MEMMEM = YesPlease
 	NO_HSTRERROR = YesPlease
 	NO_MKDTEMP = YesPlease
-	OLD_ICONV = UnfortunatelyYes
+	ifneq ($(uname_R),5.11)
+		OLD_ICONV = UnfortunatelyYes
+	endif
 	ifeq ($(uname_R),5.8)
 		NO_UNSETENV = YesPlease
 		NO_SETENV = YesPlease
diff --git a/git-compat-util.h b/git-compat-util.h
index c7cf2d5d9c..4236647c91 100644
--- a/git-compat-util.h
+++ b/git-compat-util.h
@@ -41,8 +41,10 @@
 
 #if !defined(__APPLE__) && !defined(__FreeBSD__)  && !defined(__USLC__) && !defined(_M_UNIX)
 #define _XOPEN_SOURCE 600 /* glibc2 and AIX 5.3L need 500, OpenBSD needs 600 for S_ISLNK() */
+#ifndef __sun__
 #define _XOPEN_SOURCE_EXTENDED 1 /* AIX 5.3L needs this */
 #endif
+#endif
 #define _ALL_SOURCE 1
 #define _GNU_SOURCE 1
 #define _BSD_SOURCE 1