diff --git a/src/runtime/defs_aix.go b/src/runtime/defs_aix.go
index 812c7fcfa2..bc5101f35d 100644
--- a/src/runtime/defs_aix.go
+++ b/src/runtime/defs_aix.go
@@ -65,7 +65,7 @@ const (
 	_PROT_WRITE = C.PROT_WRITE
 	_PROT_EXEC  = C.PROT_EXEC
 
-	_MAP_ANONYMOUS = C.MAP_ANONYMOUS
+	_MAP_ANON      = C.MAP_ANONYMOUS
 	_MAP_PRIVATE   = C.MAP_PRIVATE
 	_MAP_FIXED     = C.MAP_FIXED
 	_MADV_DONTNEED = C.MADV_DONTNEED
diff --git a/src/runtime/defs_aix_ppc64.go b/src/runtime/defs_aix_ppc64.go
index db17b90496..dccc3a5926 100644
--- a/src/runtime/defs_aix_ppc64.go
+++ b/src/runtime/defs_aix_ppc64.go
@@ -22,7 +22,7 @@ const (
 	_PROT_WRITE = 0x2
 	_PROT_EXEC  = 0x4
 
-	_MAP_ANONYMOUS = 0x10
+	_MAP_ANON      = 0x10
 	_MAP_PRIVATE   = 0x2
 	_MAP_FIXED     = 0x100
 	_MADV_DONTNEED = 0x4
diff --git a/src/runtime/export_mmap_test.go b/src/runtime/export_mmap_test.go
index f569627bd3..6c4a4466de 100644
--- a/src/runtime/export_mmap_test.go
+++ b/src/runtime/export_mmap_test.go
@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// +build darwin dragonfly freebsd linux nacl netbsd openbsd solaris
+// +build aix darwin dragonfly freebsd linux nacl netbsd openbsd solaris
 
 // Export guts for testing.
 
diff --git a/src/runtime/mem_aix.go b/src/runtime/mem_aix.go
index f11f0aba52..56db7426af 100644
--- a/src/runtime/mem_aix.go
+++ b/src/runtime/mem_aix.go
@@ -12,7 +12,7 @@ import (
 // prevents us from allocating more stack.
 //go:nosplit
 func sysAlloc(n uintptr, sysStat *uint64) unsafe.Pointer {
-	p, err := mmap(nil, n, _PROT_READ|_PROT_WRITE, _MAP_ANONYMOUS|_MAP_PRIVATE, -1, 0)
+	p, err := mmap(nil, n, _PROT_READ|_PROT_WRITE, _MAP_ANON|_MAP_PRIVATE, -1, 0)
 	if err != 0 {
 		if err == _EACCES {
 			print("runtime: mmap: access denied\n")
@@ -46,11 +46,11 @@ func sysFree(v unsafe.Pointer, n uintptr, sysStat *uint64) {
 }
 
 func sysFault(v unsafe.Pointer, n uintptr) {
-	mmap(v, n, _PROT_NONE, _MAP_ANONYMOUS|_MAP_PRIVATE|_MAP_FIXED, -1, 0)
+	mmap(v, n, _PROT_NONE, _MAP_ANON|_MAP_PRIVATE|_MAP_FIXED, -1, 0)
 }
 
 func sysReserve(v unsafe.Pointer, n uintptr) unsafe.Pointer {
-	p, err := mmap(v, n, _PROT_NONE, _MAP_ANONYMOUS|_MAP_PRIVATE, -1, 0)
+	p, err := mmap(v, n, _PROT_NONE, _MAP_ANON|_MAP_PRIVATE, -1, 0)
 	if err != 0 {
 		return nil
 	}
@@ -63,7 +63,7 @@ func sysMap(v unsafe.Pointer, n uintptr, sysStat *uint64) {
 	// AIX does not allow mapping a range that is already mapped.
 	// So always unmap first even if it is already unmapped.
 	munmap(v, n)
-	p, err := mmap(v, n, _PROT_READ|_PROT_WRITE, _MAP_ANONYMOUS|_MAP_FIXED|_MAP_PRIVATE, -1, 0)
+	p, err := mmap(v, n, _PROT_READ|_PROT_WRITE, _MAP_ANON|_MAP_FIXED|_MAP_PRIVATE, -1, 0)
 
 	if err == _ENOMEM {
 		throw("runtime: out of memory")
diff --git a/src/runtime/runtime_mmap_test.go b/src/runtime/runtime_mmap_test.go
index 57c38bc5dc..6741e1da8d 100644
--- a/src/runtime/runtime_mmap_test.go
+++ b/src/runtime/runtime_mmap_test.go
@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// +build darwin dragonfly freebsd linux nacl netbsd openbsd solaris
+// +build aix darwin dragonfly freebsd linux nacl netbsd openbsd solaris
 
 package runtime_test
 
@@ -34,6 +34,11 @@ func TestPhysPageSize(t *testing.T) {
 		t.Fatalf("Mmap: %v", err)
 	}
 
+	if runtime.GOOS == "aix" {
+		// AIX does not allow mapping a range that is already mapped.
+		runtime.Munmap(unsafe.Pointer(uintptr(b)), 2*ps)
+	}
+
 	// Mmap should fail at a half page into the buffer.
 	_, err = runtime.Mmap(unsafe.Pointer(uintptr(b)+ps/2), ps, 0, runtime.MAP_ANON|runtime.MAP_PRIVATE|runtime.MAP_FIXED, -1, 0)
 	if err == 0 {