diff --git a/developer/building/qubes-builder-details.md b/developer/building/qubes-builder-details.md
index f3582284..ad2b79f8 100644
--- a/developer/building/qubes-builder-details.md
+++ b/developer/building/qubes-builder-details.md
@@ -10,6 +10,12 @@ ref: 65
 title: Qubes builder details
 ---
 
+
+<div class="alert alert-warning" role="alert">
+  <i class="fa fa-exclamation-circle"></i>
+  <b>Note:</b> This information concerns the old Qubes builder (v1). It supports
+  only building Qubes 4.1 or earlier.<br>The build process has been completely rewritten in <a href="https://github.com/QubesOS/qubes-builderv2/">qubes-builder v2</a>. This can be be used for building Qubes R4.1 and later, and all related components.</div>
+
 Components Makefile.builder file
 --------------------------------
 
diff --git a/developer/building/qubes-builder.md b/developer/building/qubes-builder.md
index 035a36d3..4f7b0291 100644
--- a/developer/building/qubes-builder.md
+++ b/developer/building/qubes-builder.md
@@ -10,6 +10,12 @@ ref: 64
 title: Qubes builder
 ---
 
+<div class="alert alert-warning" role="alert">
+  <i class="fa fa-exclamation-circle"></i>
+  <b>Note:</b> These instructions concern the older Qubes builder (v1). It supports
+  only building Qubes 4.1 or earlier.<br>The build process has been completely rewritten in <a href="https://github.com/QubesOS/qubes-builderv2/">qubes-builder v2</a>. This can be be used for building Qubes R4.1 and later, and all related components.
+</div>
+
 **Note: See [ISO building instructions](/doc/qubes-iso-building/) for a streamlined overview on how to use the build system.**
 
 
diff --git a/developer/building/qubes-iso-building.md b/developer/building/qubes-iso-building.md
index fe9fb452..ac075443 100644
--- a/developer/building/qubes-iso-building.md
+++ b/developer/building/qubes-iso-building.md
@@ -12,6 +12,12 @@ ref: 63
 title: Qubes ISO building
 ---
 
+<div class="alert alert-warning" role="alert">
+  <i class="fa fa-exclamation-circle"></i>
+  <b>Note:</b> These instructions concern the older Qubes builder (v1). It supports
+  only building Qubes 4.1 or earlier.<br>The build process has been completely rewritten in <a href="https://github.com/QubesOS/qubes-builderv2/">qubes-builder v2</a>. This can be be used for building Qubes R4.1 and later, and all related components.
+</div>
+
 Build Environment
 -----------------