diff --git a/extensions/ARB/ARB_gl_spirv.txt b/extensions/ARB/ARB_gl_spirv.txt
index 221deb7..0bdf145 100644
--- a/extensions/ARB/ARB_gl_spirv.txt
+++ b/extensions/ARB/ARB_gl_spirv.txt
@@ -1105,6 +1105,8 @@
         only consume an /Image/ operand whose type has its /Sampled/
         operand set to 1.
       - The /Depth/ operand of OpTypeImage is ignored.
+      - The Image Format of OpImageWrite must not be Unknown, unless the
+        StorageImageWriteWithoutFormat OpCapability was declared.
 
     *AtomicCounter* storage class:
       - Unless otherwise specified, variables declared in the AtomicCounter
@@ -2175,10 +2177,12 @@
     Rev.    Date         Author         Changes
     ----  -----------    ------------   ---------------------------------
     45    17-Sep-2019    Jon Leech      Add OpTypeBool constraint on user
-                                        interface variables in the
-                                        Validation Rules section (internal
-                                        API issue 111).
-
+                                        interface variables, and require the
+                                        StorageImageWriteWithoutFormat
+                                        capability for OpImageWrite to
+                                        Unknown formats in the Validation
+                                        Rules section (internal API issues
+                                        111 and 112, respectively).
     44    15-Feb-2019    apinheiro      Added issue 28, about interaction with
                                         ARB_get_program_binary (internal API issue 100)
     43    15-Feb-2019    apinheiro      Add uniform initializers reference and