diff --git a/tools/meson.build b/tools/meson.build
index 628845b15f..f48a90bb0f 100644
--- a/tools/meson.build
+++ b/tools/meson.build
@@ -80,7 +80,7 @@ foreach tool: gtk_tools
   exe = executable(tool_name,
     sources: tool_srcs,
     include_directories: [confinc],
-    c_args: common_cflags + [ '-DBUILD_TOOLS' ],
+    c_args: common_cflags + [ '-DBUILD_TOOLS', '-DAVIF_DEBUG' ],
     dependencies: tool_deps,
     install: true,
   )