diff --git a/video/out/opengl/utils.c b/video/out/opengl/utils.c
index fa1131e815..c0bd07fb91 100644
--- a/video/out/opengl/utils.c
+++ b/video/out/opengl/utils.c
@@ -445,6 +445,9 @@ struct sc_uniform {
     int size;
     GLint loc;
     union uniform_val v;
+    // Set for sampler uniforms.
+    GLenum tex_target;
+    GLuint tex_handle;
 };
 
 struct sc_cached_uniform {
@@ -473,6 +476,7 @@ struct gl_shader_cache {
     bstr prelude_text;
     bstr header_text;
     bstr text;
+    int next_texture_unit;
     struct gl_vao *vao;
 
     struct sc_entry *entries;
@@ -507,15 +511,26 @@ void gl_sc_reset(struct gl_shader_cache *sc)
 {
     GL *gl = sc->gl;
 
-    if (sc->needs_reset)
+    if (sc->needs_reset) {
         gl->UseProgram(0);
 
+        for (int n = 0; n < sc->num_uniforms; n++) {
+            struct sc_uniform *u = &sc->uniforms[n];
+            if (u->type == UT_i && u->tex_target) {
+                gl->ActiveTexture(GL_TEXTURE0 + u->v.i[0]);
+                gl->BindTexture(u->tex_target, 0);
+            }
+        }
+        gl->ActiveTexture(GL_TEXTURE0);
+    }
+
     sc->prelude_text.len = 0;
     sc->header_text.len = 0;
     sc->text.len = 0;
     for (int n = 0; n < sc->num_uniforms; n++)
         talloc_free(sc->uniforms[n].name);
     sc->num_uniforms = 0;
+    sc->next_texture_unit = 1; // not 0, as 0 is "free for use"
     sc->needs_reset = false;
 }
 
@@ -622,6 +637,7 @@ const char* mp_sampler_type(GLenum texture_target)
     }
 }
 
+// gl_sc_uniform_tex() should be preferred.
 void gl_sc_uniform_sampler(struct gl_shader_cache *sc, char *name, GLenum target,
                            int unit)
 {
@@ -630,15 +646,31 @@ void gl_sc_uniform_sampler(struct gl_shader_cache *sc, char *name, GLenum target
     u->size = 1;
     u->glsl_type = mp_sampler_type(target);
     u->v.i[0] = unit;
+    u->tex_target = 0;
+    u->tex_handle = 0;
 }
 
-void gl_sc_uniform_sampler_ui(struct gl_shader_cache *sc, char *name, int unit)
+void gl_sc_uniform_tex(struct gl_shader_cache *sc, char *name, GLenum target,
+                       GLuint texture)
+{
+    struct sc_uniform *u = find_uniform(sc, name);
+    u->type = UT_i;
+    u->size = 1;
+    u->glsl_type = mp_sampler_type(target);
+    u->v.i[0] = sc->next_texture_unit++;
+    u->tex_target = target;
+    u->tex_handle = texture;
+}
+
+void gl_sc_uniform_tex_ui(struct gl_shader_cache *sc, char *name, GLuint texture)
 {
     struct sc_uniform *u = find_uniform(sc, name);
     u->type = UT_i;
     u->size = 1;
     u->glsl_type = sc->gl->es ? "highp usampler2D" : "usampler2D";
-    u->v.i[0] = unit;
+    u->v.i[0] = sc->next_texture_unit++;
+    u->tex_target = GL_TEXTURE_2D;
+    u->tex_handle = texture;
 }
 
 void gl_sc_uniform_f(struct gl_shader_cache *sc, char *name, GLfloat f)
@@ -755,6 +787,11 @@ static void update_uniform(GL *gl, struct sc_entry *e, struct sc_uniform *u, int
             memcpy(un->v.i, u->v.i, sizeof(u->v.i));
             gl->Uniform1i(loc, u->v.i[0]);
         }
+        // For samplers: set the actual texture.
+        if (u->tex_target) {
+            gl->ActiveTexture(GL_TEXTURE0 + u->v.i[0]);
+            gl->BindTexture(u->tex_target, u->tex_handle);
+        }
         break;
     case UT_f:
         if (memcmp(un->v.f, u->v.f, sizeof(u->v.f)) != 0) {
diff --git a/video/out/opengl/utils.h b/video/out/opengl/utils.h
index ab3c13c915..33c2daa5be 100644
--- a/video/out/opengl/utils.h
+++ b/video/out/opengl/utils.h
@@ -156,7 +156,9 @@ void gl_sc_haddf(struct gl_shader_cache *sc, const char *textf, ...);
 void gl_sc_hadd_bstr(struct gl_shader_cache *sc, struct bstr text);
 void gl_sc_uniform_sampler(struct gl_shader_cache *sc, char *name, GLenum target,
                            int unit);
-void gl_sc_uniform_sampler_ui(struct gl_shader_cache *sc, char *name, int unit);
+void gl_sc_uniform_tex(struct gl_shader_cache *sc, char *name, GLenum target,
+                       GLuint texture);
+void gl_sc_uniform_tex_ui(struct gl_shader_cache *sc, char *name, GLuint texture);
 void gl_sc_uniform_f(struct gl_shader_cache *sc, char *name, GLfloat f);
 void gl_sc_uniform_i(struct gl_shader_cache *sc, char *name, GLint f);
 void gl_sc_uniform_vec2(struct gl_shader_cache *sc, char *name, GLfloat f[2]);
diff --git a/video/out/opengl/video.c b/video/out/opengl/video.c
index b000b2e7ce..4121ff785c 100644
--- a/video/out/opengl/video.c
+++ b/video/out/opengl/video.c
@@ -673,7 +673,6 @@ static bool gl_video_get_lut3d(struct gl_video *p, enum mp_csp_prim prim,
     if (!p->lut_3d_texture)
         gl->GenTextures(1, &p->lut_3d_texture);
 
-    gl->ActiveTexture(GL_TEXTURE0 + TEXUNIT_3DLUT);
     gl->BindTexture(GL_TEXTURE_3D, p->lut_3d_texture);
     gl->PixelStorei(GL_UNPACK_ALIGNMENT, 1);
     gl->TexImage3D(GL_TEXTURE_3D, 0, GL_RGB16, lut3d->size[0], lut3d->size[1],
@@ -684,7 +683,7 @@ static bool gl_video_get_lut3d(struct gl_video *p, enum mp_csp_prim prim,
     gl->TexParameteri(GL_TEXTURE_3D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
     gl->TexParameteri(GL_TEXTURE_3D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
     gl->TexParameteri(GL_TEXTURE_3D, GL_TEXTURE_WRAP_R, GL_CLAMP_TO_EDGE);
-    gl->ActiveTexture(GL_TEXTURE0);
+    gl->BindTexture(GL_TEXTURE_3D, 0);
 
     debug_check_gl(p, "after 3d lut creation");
 
@@ -946,7 +945,6 @@ static void uninit_video(struct gl_video *p)
 
 static void pass_prepare_src_tex(struct gl_video *p)
 {
-    GL *gl = p->gl;
     struct gl_shader_cache *sc = p->sc;
 
     for (int n = 0; n < p->pass_tex_num; n++) {
@@ -964,9 +962,9 @@ static void pass_prepare_src_tex(struct gl_video *p)
         snprintf(pixel_size, sizeof(pixel_size), "pixel_size%d", n);
 
         if (s->use_integer) {
-            gl_sc_uniform_sampler_ui(sc, texture_name, n);
+            gl_sc_uniform_tex_ui(sc, texture_name, s->gl_tex);
         } else {
-            gl_sc_uniform_sampler(sc, texture_name, s->gl_target, n);
+            gl_sc_uniform_tex(sc, texture_name, s->gl_target, s->gl_tex);
         }
         float f[2] = {1, 1};
         if (s->gl_target != GL_TEXTURE_RECTANGLE) {
@@ -977,11 +975,7 @@ static void pass_prepare_src_tex(struct gl_video *p)
         gl_sc_uniform_mat2(sc, texture_rot, true, (float *)s->transform.m);
         gl_sc_uniform_vec2(sc, pixel_size, (GLfloat[]){1.0f / f[0],
                                                        1.0f / f[1]});
-
-        gl->ActiveTexture(GL_TEXTURE0 + n);
-        gl->BindTexture(s->gl_target, s->gl_tex);
     }
-    gl->ActiveTexture(GL_TEXTURE0);
 }
 
 static void render_pass_quad(struct gl_video *p, int vp_w, int vp_h,
@@ -1401,8 +1395,6 @@ static void reinit_scaler(struct gl_video *p, struct scaler *scaler,
     const struct gl_format *fmt = gl_find_float16_format(gl, elems_per_pixel);
     GLenum target = scaler->gl_target;
 
-    gl->ActiveTexture(GL_TEXTURE0 + TEXUNIT_SCALERS + scaler->index);
-
     if (!scaler->gl_lut)
         gl->GenTextures(1, &scaler->gl_lut);
 
@@ -1429,7 +1421,7 @@ static void reinit_scaler(struct gl_video *p, struct scaler *scaler,
     if (target != GL_TEXTURE_1D)
         gl->TexParameteri(target, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
 
-    gl->ActiveTexture(GL_TEXTURE0);
+    gl->BindTexture(target, 0);
 
     debug_check_gl(p, "after initializing scaler");
 }
@@ -2184,7 +2176,7 @@ static void pass_colormanage(struct gl_video *p, struct mp_colorspace src, bool
                    p->opts.tone_mapping_param);
 
     if (p->use_lut_3d) {
-        gl_sc_uniform_sampler(p->sc, "lut_3d", GL_TEXTURE_3D, TEXUNIT_3DLUT);
+        gl_sc_uniform_tex(p->sc, "lut_3d", GL_TEXTURE_3D, p->lut_3d_texture);
         GLSL(vec3 cpos;)
         for (int i = 0; i < 3; i++)
             GLSLF("cpos[%d] = LUT_POS(color[%d], %d.0);\n", i, i, p->lut_3d_size[i]);
@@ -2250,7 +2242,6 @@ static void pass_dither(struct gl_video *p)
 
         p->dither_size = tex_size;
 
-        gl->ActiveTexture(GL_TEXTURE0 + TEXUNIT_DITHER);
         gl->GenTextures(1, &p->dither_texture);
         gl->BindTexture(GL_TEXTURE_2D, p->dither_texture);
         gl->PixelStorei(GL_UNPACK_ALIGNMENT, 1);
@@ -2261,7 +2252,7 @@ static void pass_dither(struct gl_video *p)
         gl->TexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);
         gl->TexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);
         gl->PixelStorei(GL_UNPACK_ALIGNMENT, 4);
-        gl->ActiveTexture(GL_TEXTURE0);
+        gl->BindTexture(GL_TEXTURE_2D, 0);
 
         debug_check_gl(p, "dither setup");
     }
@@ -2274,7 +2265,7 @@ static void pass_dither(struct gl_video *p)
     // dither patterns can be visible.
     int dither_quantization = (1 << dst_depth) - 1;
 
-    gl_sc_uniform_sampler(p->sc, "dither", GL_TEXTURE_2D, TEXUNIT_DITHER);
+    gl_sc_uniform_tex(p->sc, "dither", GL_TEXTURE_2D, p->dither_texture);
 
     GLSLF("vec2 dither_pos = gl_FragCoord.xy / %d.0;\n", p->dither_size);
 
diff --git a/video/out/opengl/video.h b/video/out/opengl/video.h
index a6c7ca2898..9c76c4a454 100644
--- a/video/out/opengl/video.h
+++ b/video/out/opengl/video.h
@@ -27,14 +27,10 @@
 #include "lcms.h"
 #include "video/out/filter_kernels.h"
 
-// Texture units 0-5 are used by the video, and for free use by the passes
+// Assume we have this many texture units for sourcing additional passes.
+// The actual texture unit assignment is dynamic.
 #define TEXUNIT_VIDEO_NUM 6
 
-// Other texture units are reserved for specific purposes
-#define TEXUNIT_SCALERS  TEXUNIT_VIDEO_NUM
-#define TEXUNIT_3DLUT    (TEXUNIT_SCALERS+SCALER_COUNT)
-#define TEXUNIT_DITHER   (TEXUNIT_3DLUT+1)
-
 struct scaler_fun {
     char *name;
     float params[2];
diff --git a/video/out/opengl/video_shaders.c b/video/out/opengl/video_shaders.c
index ff87b99b62..7d668dc4b8 100644
--- a/video/out/opengl/video_shaders.c
+++ b/video/out/opengl/video_shaders.c
@@ -38,8 +38,7 @@ void sampler_prelude(struct gl_shader_cache *sc, int tex_num)
 static void pass_sample_separated_get_weights(struct gl_shader_cache *sc,
                                               struct scaler *scaler)
 {
-    gl_sc_uniform_sampler(sc, "lut", scaler->gl_target,
-                          TEXUNIT_SCALERS + scaler->index);
+    gl_sc_uniform_tex(sc, "lut", scaler->gl_target, scaler->gl_lut);
     // Define a new variable to cache the corrected fcoord.
     GLSLF("float fcoord_lut = LUT_POS(fcoord, %d.0);\n", scaler->lut_size);
 
@@ -121,8 +120,7 @@ void pass_sample_polar(struct gl_shader_cache *sc, struct scaler *scaler)
         GLSL(vec4 lo = vec4(1.0);)
         GLSL(vec4 hi = vec4(0.0);)
     }
-    gl_sc_uniform_sampler(sc, "lut", scaler->gl_target,
-                          TEXUNIT_SCALERS + scaler->index);
+    gl_sc_uniform_tex(sc, "lut", scaler->gl_target, scaler->gl_lut);
     GLSLF("// scaler samples\n");
     for (int y = 1-bound; y <= bound; y++) {
         for (int x = 1-bound; x <= bound; x++) {