diff --git a/src/common.h b/src/common.h
index df9c7f5..d229bf4 100644
--- a/src/common.h
+++ b/src/common.h
@@ -107,10 +107,15 @@ typedef struct glx_prog_main {
 	GLint unifm_invert_color;
 	/// Location of uniform "tex" in window GLSL program.
 	GLint unifm_tex;
+	/// Location of uniform "time" in window GLSL program.
+	GLint unifm_time;
 } glx_prog_main_t;
 
 #define GLX_PROG_MAIN_INIT                                                               \
-	{ .prog = 0, .unifm_opacity = -1, .unifm_invert_color = -1, .unifm_tex = -1, }
+	{                                                                                \
+		.prog = 0, .unifm_opacity = -1, .unifm_invert_color = -1,                \
+		.unifm_tex = -1, .unifm_time = -1                                        \
+	}
 
 #else
 struct glx_prog_main {};
diff --git a/src/opengl.c b/src/opengl.c
index e5a57ca..0a80c6d 100644
--- a/src/opengl.c
+++ b/src/opengl.c
@@ -12,6 +12,7 @@
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
+#include <time.h>
 #include <xcb/render.h>
 #include <xcb/xcb.h>
 
@@ -442,6 +443,7 @@ bool glx_load_prog_main(const char *vshader_str, const char *fshader_str,
 	P_GET_UNIFM_LOC("opacity", unifm_opacity);
 	P_GET_UNIFM_LOC("invert_color", unifm_invert_color);
 	P_GET_UNIFM_LOC("tex", unifm_tex);
+	P_GET_UNIFM_LOC("time", unifm_time);
 #undef P_GET_UNIFM_LOC
 
 	gl_check_err();
@@ -1029,12 +1031,16 @@ bool glx_render(session_t *ps, const glx_texture_t *ptex, int x, int y, int dx,
 		// Programmable path
 		assert(pprogram->prog);
 		glUseProgram(pprogram->prog);
+		struct timespec ts;
+		clock_gettime(CLOCK_MONOTONIC, &ts);
 		if (pprogram->unifm_opacity >= 0)
 			glUniform1f(pprogram->unifm_opacity, (float)opacity);
 		if (pprogram->unifm_invert_color >= 0)
 			glUniform1i(pprogram->unifm_invert_color, neg);
 		if (pprogram->unifm_tex >= 0)
 			glUniform1i(pprogram->unifm_tex, 0);
+		if (pprogram->unifm_time >= 0)
+			glUniform1f(pprogram->unifm_time, (float)ts.tv_sec * 1000.0f + (float)ts.tv_nsec / 1.0e6f);
 	}
 
 	// log_trace("Draw: %d, %d, %d, %d -> %d, %d (%d, %d) z %d", x, y, width, height,