diff --git a/src/mesa/main/image.c b/src/mesa/main/image.c
index d77c593ac7c..006a55116bc 100644
--- a/src/mesa/main/image.c
+++ b/src/mesa/main/image.c
@@ -688,6 +688,22 @@ _mesa_is_depth_format(GLenum format)
 }
 
 
+/**
+ * Test if the given image format is a stencil format.
+ */
+GLboolean
+_mesa_is_stencil_format(GLenum format)
+{
+   switch (format) {
+      case GL_STENCIL_INDEX:
+      case GL_DEPTH_STENCIL:
+         return GL_TRUE;
+      default:
+         return GL_FALSE;
+   }
+}
+
+
 /**
  * Test if the given image format is a YCbCr format.
  */
diff --git a/src/mesa/main/image.h b/src/mesa/main/image.h
index 20459a5f1e1..a082f374571 100644
--- a/src/mesa/main/image.h
+++ b/src/mesa/main/image.h
@@ -63,6 +63,9 @@ _mesa_is_index_format(GLenum format);
 extern GLboolean
 _mesa_is_depth_format(GLenum format);
 
+extern GLboolean
+_mesa_is_stencil_format(GLenum format);
+
 extern GLboolean
 _mesa_is_ycbcr_format(GLenum format);