diff --git a/src/common.h b/src/common.h
index 55fff919..bf97d382 100644
--- a/src/common.h
+++ b/src/common.h
@@ -167,6 +167,7 @@
 #include "xrescheck.h"
 #endif
 
+#include "types.h"
 #include "x.h"
 #include "region.h"
 
@@ -220,7 +221,6 @@
 
 // === Types ===
 
-typedef uint32_t opacity_t;
 typedef long time_ms_t;
 typedef struct _c2_lptr c2_lptr_t;
 
@@ -243,31 +243,7 @@ typedef enum {
   NUM_WINTYPES
 } wintype_t;
 
-/// Enumeration type to represent switches.
-typedef enum {
-  OFF,    // false
-  ON,     // true
-  UNSET
-} switch_t;
-
-/// Structure representing a X geometry.
-typedef struct {
-  int wid;
-  int hei;
-  int x;
-  int y;
-} geometry_t;
-
-/// A structure representing margins around a rectangle.
-typedef struct {
-  int top;
-  int left;
-  int bottom;
-  int right;
-} margin_t;
-
 // Or use cmemzero().
-#define MARGIN_INIT { 0, 0, 0, 0 }
 
 /// Enumeration type of window painting mode.
 typedef enum {
diff --git a/src/region.h b/src/region.h
index e347d2ed..a42f9f2e 100644
--- a/src/region.h
+++ b/src/region.h
@@ -5,6 +5,7 @@
 #include <pixman.h>
 #include <stdio.h>
 #include "utils.h"
+
 typedef struct pixman_region32 pixman_region32_t;
 typedef struct pixman_box32 pixman_box32_t;
 typedef pixman_region32_t region_t;
diff --git a/src/types.h b/src/types.h
new file mode 100644
index 00000000..58d198c7
--- /dev/null
+++ b/src/types.h
@@ -0,0 +1,33 @@
+// SPDX-License-Identifier: MPL-2.0
+// Copyright (c) 2018 Yuxuan Shui <yshuiv7@gmail.com>
+
+/// Some common types
+
+#include <stdint.h>
+
+/// Enumeration type to represent switches.
+typedef enum {
+  OFF,    // false
+  ON,     // true
+  UNSET
+} switch_t;
+
+/// Structure representing a X geometry.
+typedef struct {
+  int wid;
+  int hei;
+  int x;
+  int y;
+} geometry_t;
+
+/// A structure representing margins around a rectangle.
+typedef struct {
+  int top;
+  int left;
+  int bottom;
+  int right;
+} margin_t;
+
+typedef uint32_t opacity_t;
+
+#define MARGIN_INIT { 0, 0, 0, 0 }