Remove references to umask from build system.
diff --git a/CMakeLists.txt b/CMakeLists.txt
index 6dc97fa..4b7a116 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -140,7 +140,6 @@
 CHECK_FUNCTION_EXISTS(_stricmp HAVE__STRICMP)
 CHECK_FUNCTION_EXISTS(_strtoi64 HAVE__STRTOI64)
 CHECK_FUNCTION_EXISTS(_strtoui64 HAVE__STRTOUI64)
-CHECK_FUNCTION_EXISTS(_umask HAVE__UMASK)
 CHECK_FUNCTION_EXISTS(_unlink HAVE__UNLINK)
 CHECK_FUNCTION_EXISTS(clonefile HAVE_CLONEFILE)
 CHECK_FUNCTION_EXISTS(explicit_bzero HAVE_EXPLICIT_BZERO)
diff --git a/lib/compat.h b/lib/compat.h
index 79f94db..78f40a4 100644
--- a/lib/compat.h
+++ b/lib/compat.h
@@ -116,9 +116,6 @@
 #if !defined(HAVE_STRTOULL) && defined(HAVE__STRTOUI64)
 #define strtoull _strtoui64
 #endif
-#if defined(HAVE__UMASK)
-#define umask _umask
-#endif
 #if defined(HAVE__UNLINK)
 #define unlink _unlink
 #endif