diff --git a/headers/posix/sys/mman.h b/headers/posix/sys/mman.h
index a69991ac05..40c49c7b5d 100644
--- a/headers/posix/sys/mman.h
+++ b/headers/posix/sys/mman.h
@@ -23,6 +23,7 @@
 #define MAP_FIXED		0x04			/* require mapping to specified addr */
 #define MAP_ANONYMOUS	0x08			/* no underlying object */
 #define MAP_ANON		MAP_ANONYMOUS
+#define MAP_NORESERVE	0x10			/* don't commit memory */
 
 /* mmap() error return code */
 #define MAP_FAILED		((void*)-1)
diff --git a/src/system/libroot/posix/sys/mman.cpp b/src/system/libroot/posix/sys/mman.cpp
index 8de57a3dd7..3944538ef9 100644
--- a/src/system/libroot/posix/sys/mman.cpp
+++ b/src/system/libroot/posix/sys/mman.cpp
@@ -131,8 +131,9 @@ mmap(void* address, size_t length, int protection, int flags, int fd,
 		areaProtection |= B_WRITE_AREA;
 	if ((protection & PROT_EXEC) != 0)
 		areaProtection |= B_EXECUTE_AREA;
-	if (protection == PROT_NONE)
-		areaProtection = B_OVERCOMMITTING_AREA;
+
+	if ((flags & MAP_NORESERVE) != 0)
+		areaProtection |= B_OVERCOMMITTING_AREA;
 
 	// create a name for this area based on calling image
 	void* addr = __builtin_return_address(0);