diff --git a/docs/glsl.md b/docs/glsl.md
index 08996cdc..c45e7842 100644
--- a/docs/glsl.md
+++ b/docs/glsl.md
@@ -313,7 +313,7 @@ size_t _glsl_330_fn(void *alloc, pl_str *buf, const uint8_t *ptr)
     } vars;
     memcpy(&vars, ptr, sizeof(vars));
 
-    pl_str_append_asprintf(alloc, buf,
+    pl_str_append_asprintf_c(alloc, buf,
         "/* pl_shader_sample_bicubic */\n"
         "    vec4 color;\n"
         "    {\n"
diff --git a/tools/glsl_preproc/templates/glsl_block.c.j2 b/tools/glsl_preproc/templates/glsl_block.c.j2
index 1ad36132..aa8372d1 100644
--- a/tools/glsl_preproc/templates/glsl_block.c.j2
+++ b/tools/glsl_preproc/templates/glsl_block.c.j2
@@ -1,6 +1,6 @@
 #line {{ block.linenr }}
 {% if block.refs %}
-    pl_str_append_asprintf(alloc, buf,
+    pl_str_append_asprintf_c(alloc, buf,
     {% for line in block.lines %}
         {{ line.fmtstr }}{{ ',' if loop.last }}
     {% endfor %}