diff --git a/include/effect.h b/include/effect.h
index 4b1e4a2..1b696e1 100644
--- a/include/effect.h
+++ b/include/effect.h
@@ -72,6 +72,7 @@ enum effect {
 	EFFECT_BLUR_FADEOUT           = 50,
 	EFFECT_BLUR_CROSSFADE         = 51,
 	EFFECT_2ROT_ZOOM_BLEND_BLUR   = 52,
+	EFFECT_VWAVE_CROSSFADE        = 60,
 	NR_EFFECTS
 };
 
diff --git a/shaders/effects/vwave_crossfade.f.glsl b/shaders/effects/vwave_crossfade.f.glsl
new file mode 100644
index 0000000..6f4c36f
--- /dev/null
+++ b/shaders/effects/vwave_crossfade.f.glsl
@@ -0,0 +1,39 @@
+/* Copyright (C) 2019 Nunuhara Cabbage <nunuhara@haniwa.technology>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, see <http://gnu.org/licenses/>.
+ */
+
+uniform sampler2D tex;   // the new scene
+uniform sampler2D old;   // the old scene
+uniform vec2 resolution; // the screen resolution
+uniform float progress;  // effect progress (0..1)
+
+in vec2 tex_coord;
+out vec4 frag_color;
+
+vec3 get_pixel(vec2 xy) {
+        return mix(texture(old, xy).rgb, texture(tex, xy).rgb, progress);
+}
+
+float triangle(float f) {
+        return 1.0 - abs(f * 2.0 - 1.0);
+}
+
+void main() {
+        vec2 p = tex_coord * resolution;
+        float scale = triangle(progress) * 80.0; // (0..0.5..1) -> (0..80..0);
+        float wobble = progress * 24.0;
+        float offset = sin((p.y / 100.0) - wobble) * scale;
+        frag_color = vec4(get_pixel(fract(vec2(p.x + offset, p.y) / resolution)), 1.0);
+}
diff --git a/src/effect.c b/src/effect.c
index 7668c9d..1484d71 100644
--- a/src/effect.c
+++ b/src/effect.c
@@ -75,6 +75,7 @@ const char *effect_names[NR_EFFECTS] = {
 	[EFFECT_BLUR_FADEOUT]           = "EFFECT_BLUR_FADEOUT",
 	[EFFECT_BLUR_CROSSFADE]         = "EFFECT_BLUR_CROSSFADE",
 	[EFFECT_2ROT_ZOOM_BLEND_BLUR]   = "EFFECT_2ROT_ZOOM_BLEND_BLUR",
+	[EFFECT_VWAVE_CROSSFADE]        = "EFFECT_VWAVE_CROSSFADE",
 };
 
 struct effect_shader {
@@ -153,6 +154,7 @@ static struct effect_shader turn_page_shader = EFFECT_SHADER("shaders/effects/tu
 static struct effect_shader sepia_noise_crossfade_shader = EFFECT_SHADER("shaders/effects/sepia_noise_crossfade.f.glsl");
 static struct effect_shader blur_fadeout_shader = EFFECT_SHADER("shaders/effects/blur_fadeout.f.glsl");
 static struct effect_shader blur_crossfade_shader = EFFECT_SHADER("shaders/effects/blur_crossfade.f.glsl");
+static struct effect_shader vwave_crossfade_shader = EFFECT_SHADER("shaders/effects/vwave_crossfade.f.glsl");
 
 static struct effect_shader *effect_shaders[NR_EFFECTS] = {
 	[EFFECT_CROSSFADE] = &crossfade_shader,
@@ -168,6 +170,7 @@ static struct effect_shader *effect_shaders[NR_EFFECTS] = {
 	[EFFECT_SEPIA_NOISE_CROSSFADE] = &sepia_noise_crossfade_shader,
 	[EFFECT_BLUR_FADEOUT] = &blur_fadeout_shader,
 	[EFFECT_BLUR_CROSSFADE] = &blur_crossfade_shader,
+	[EFFECT_VWAVE_CROSSFADE] = &vwave_crossfade_shader,
 };
 
 static void effect_fadeout(Texture *dst, Texture *old, Texture *new, float rate)
@@ -274,7 +277,10 @@ void effect_update_texture(int type, Texture *dst, Texture *old, Texture *new, f
 	} else {
 		struct effect_shader *s = effect_shaders[type];
 		if (!s) {
-			WARNING("Unimplemented effect: %s", effect_names[type]);
+			if (effect_names[type])
+				WARNING("Unimplemented effect: %s", effect_names[type]);
+			else
+				WARNING("Unimplemented effect: %d", type);
 			s = effect_shaders[EFFECT_BLUR_CROSSFADE];
 		}
 		if (!s->s.program)
@@ -296,7 +302,10 @@ int effect_init(enum effect type)
 	else {
 		struct effect_shader *s = effect_shaders[type];
 		if (!s) {
-			WARNING("Unimplemented effect: %s", effect_names[type]);
+			if (effect_names[type])
+				WARNING("Unimplemented effect: %s", effect_names[type]);
+			else
+				WARNING("Unimplemented effect: %d", type);
 			type = EFFECT_BLUR_CROSSFADE;
 			s = effect_shaders[type];
 		}