diff --git a/src/compiler/glsl/gl_nir_linker.c b/src/compiler/glsl/gl_nir_linker.c
index fd51bf5a43f..c5e3b91cde7 100644
--- a/src/compiler/glsl/gl_nir_linker.c
+++ b/src/compiler/glsl/gl_nir_linker.c
@@ -1471,9 +1471,6 @@ gl_nir_lower_optimize_varyings(const struct gl_constants *consts,
    unsigned max_ubos = UINT_MAX;
    unsigned max_uniform_comps = UINT_MAX;
 
-   if (debug_get_bool_option("MESA_GLSL_DISABLE_IO_OPT", false))
-      return;
-
    for (unsigned i = 0; i < MESA_SHADER_STAGES; i++) {
       struct gl_linked_shader *shader = prog->_LinkedShaders[i];
 
@@ -1496,6 +1493,9 @@ gl_nir_lower_optimize_varyings(const struct gl_constants *consts,
    for (unsigned i = 0; i < num_shaders; i++)
       nir_lower_io_passes(shaders[i], true);
 
+   if (debug_get_bool_option("MESA_GLSL_DISABLE_IO_OPT", false))
+      return;
+
    /* There is nothing to optimize for only 1 shader. */
    if (num_shaders == 1) {
       nir_shader *nir = shaders[0];