diff --git a/src/tint/lang/glsl/writer/printer/printer.cc b/src/tint/lang/glsl/writer/printer/printer.cc
index d02ccce..c4cc0fd 100644
--- a/src/tint/lang/glsl/writer/printer/printer.cc
+++ b/src/tint/lang/glsl/writer/printer/printer.cc
@@ -730,7 +730,7 @@
                             case core::TexelFormat::kR32Uint:
                                 break;
                             default:
-                                TINT_UNREACHABLE();
+                                TINT_UNREACHABLE() << "invalid texel format for read-write";
                         }
                     }
                     break;