diff --git a/docs/reference/gtk/running.md b/docs/reference/gtk/running.md
index 78e7c3ac86..848f1d44c9 100644
--- a/docs/reference/gtk/running.md
+++ b/docs/reference/gtk/running.md
@@ -347,6 +347,28 @@ a `*`, which means: try all remaining backends. The special value
 backends. For more information about selecting backends,
 see the [func@Gdk.DisplayManager.get] function.
 
+### `GDK_GL_DISABLE`
+
+This variable can be set to a list of values, which cause GDK to
+disable extension features of the OpenGL support.
+Note that these features may already be disabled if the GL driver
+does not support them.
+
+`debug`
+: GL_KHR_debug
+
+`unpack-subimage`
+:GL_EXT_unpack_subimage
+
+`half-float`
+:GL_OES_vertex_half_float
+
+`sync`
+:GL_ARB_sync
+
+`bgra`
+:GL_EXT_texture_format_BGRA8888
+
 ### `GDK_VULKAN_DEVICE`
 
 This variable can be set to the index of a Vulkan device to override
diff --git a/gdk/gdkglcontext.c b/gdk/gdkglcontext.c
index 9676052df3..3fcd1288be 100644
--- a/gdk/gdkglcontext.c
+++ b/gdk/gdkglcontext.c
@@ -103,6 +103,14 @@
 
 #define DEFAULT_ALLOWED_APIS GDK_GL_API_GL | GDK_GL_API_GLES
 
+static const GdkDebugKey gdk_gl_feature_keys[] = {
+  { "debug", GDK_GL_FEATURE_DEBUG, "GL_KHR_debug" },
+  { "unpack-subimage", GDK_GL_FEATURE_UNPACK_SUBIMAGE, "GL_EXT_unpack_subimage" },
+  { "half-float", GDK_GL_FEATURE_VERTEX_HALF_FLOAT, "GL_OES_vertex_half_float" },
+  { "sync", GDK_GL_FEATURE_SYNC, "GL_ARB_sync" },
+  { "bgra", GDK_GL_FEATURE_BGRA, "GL_EXT_texture_format_BGRA8888" },
+};
+
 typedef struct _GdkGLContextPrivate GdkGLContextPrivate;
 
 struct _GdkGLContextPrivate
@@ -1699,6 +1707,7 @@ static void
 gdk_gl_context_check_extensions (GdkGLContext *context)
 {
   GdkGLContextPrivate *priv = gdk_gl_context_get_instance_private (context);
+  GdkGLFeatures supported_features, disabled_features;
   gboolean gl_debug = FALSE;
   GdkDisplay *display;
 
@@ -1726,7 +1735,12 @@ gdk_gl_context_check_extensions (GdkGLContext *context)
       !gdk_gl_version_greater_equal (&priv->gl_version, &GDK_GL_VERSION_INIT (3, 2)))
     priv->is_legacy = TRUE;
 
-  priv->features = gdk_gl_context_check_features (context);
+  supported_features = gdk_gl_context_check_features (context);
+  disabled_features = gdk_parse_debug_var ("GDK_GL_DISABLE",
+                                           gdk_gl_feature_keys,
+                                           G_N_ELEMENTS (gdk_gl_feature_keys));
+
+  priv->features = supported_features & ~disabled_features;
 
   gdk_gl_context_init_memory_flags (context);
 
@@ -1736,19 +1750,29 @@ gdk_gl_context_check_extensions (GdkGLContext *context)
       glGetIntegerv (GL_MAX_LABEL_LENGTH, &priv->max_debug_label_length);
     }
 
-  {
-    int max_texture_size;
-    glGetIntegerv (GL_MAX_TEXTURE_SIZE, &max_texture_size);
-    GDK_DISPLAY_DEBUG (gdk_draw_context_get_display (GDK_DRAW_CONTEXT (context)), OPENGL,
-                       "%s version: %d.%d (%s)\n"
-                       "* GLSL version: %s\n"
-                       "* Max texture size: %d\n",
-                       gdk_gl_context_get_use_es (context) ? "OpenGL ES" : "OpenGL",
-                       gdk_gl_version_get_major (&priv->gl_version), gdk_gl_version_get_minor (&priv->gl_version),
-                       priv->is_legacy ? "legacy" : "core",
-                       glGetString (GL_SHADING_LANGUAGE_VERSION),
-                       max_texture_size);
-  }
+  if (GDK_DISPLAY_DEBUG_CHECK (display, OPENGL))
+    {
+      int i, max_texture_size;
+      glGetIntegerv (GL_MAX_TEXTURE_SIZE, &max_texture_size);
+      gdk_debug_message ("%s version: %d.%d (%s)\n"
+                         "* GLSL version: %s\n"
+                         "* Max texture size: %d\n",
+                         gdk_gl_context_get_use_es (context) ? "OpenGL ES" : "OpenGL",
+                         gdk_gl_version_get_major (&priv->gl_version), gdk_gl_version_get_minor (&priv->gl_version),
+                         priv->is_legacy ? "legacy" : "core",
+                         glGetString (GL_SHADING_LANGUAGE_VERSION),
+                         max_texture_size);
+      gdk_debug_message ("Enabled features (use GDK_GL_DISABLE env var to disable):");
+      for (i = 0; i < G_N_ELEMENTS (gdk_gl_feature_keys); i++)
+        {
+          gdk_debug_message ("    %s: %s",
+                             gdk_gl_feature_keys[i].key,
+                             (priv->features & gdk_gl_feature_keys[i].value) ? "YES" :
+                             ((disabled_features & gdk_gl_feature_keys[i].value) ? "disabled via env var" :
+                             (((supported_features & gdk_gl_feature_keys[i].value) == 0) ? "not supported" :
+                             "Hum, what? This should not happen.")));
+        }
+    }
 
   priv->extensions_checked = TRUE;
 }