diff --git a/ChangeLog b/ChangeLog
index da204bdc..323e162d 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -4,7 +4,7 @@ Unreleased
   * You can now pass null to ImagickDraw::setStrokeDashArray() to reset the dash array.
 - Added:
   * function Imagick::clutImageWithInterpolate(Imagick $lookup_table, int $pixel_interpolate_method): bool  {}
-  * Constants Imagick::COMPRESSION_BC5, Imagick::COMPRESSION_BC7, Imagick::COMPRESSION_LERC, Imagick::DIRECTION_TOP_TO_BOTTOM
+  * Constants Imagick::COMPRESSION_BC5, Imagick::COMPRESSION_BC7, Imagick::COMPRESSION_LERC, Imagick::DIRECTION_TOP_TO_BOTTOM, Imagick::ALPHACHANNEL_OFF_IF_OPAQUE
 
 3.7.0
 - Added:
diff --git a/imagick_helpers.c b/imagick_helpers.c
index 6d446617..02f1581c 100644
--- a/imagick_helpers.c
+++ b/imagick_helpers.c
@@ -1823,6 +1823,13 @@ void php_imagick_initialize_constants(TSRMLS_D)
 	IMAGICK_REGISTER_CONST_LONG("ALPHACHANNEL_ASSOCIATE", AssociateAlphaChannel);
 	IMAGICK_REGISTER_CONST_LONG("ALPHACHANNEL_DISSOCIATE", DisassociateAlphaChannel);
 #endif
+
+#if MagickLibVersion >= 0x712
+	// Technically >= 7.1.1-26 but we still don't have a mechanism for
+	// detecting patch versions.
+	IMAGICK_REGISTER_CONST_LONG("ALPHACHANNEL_OFF_IF_OPAQUE", OffIfOpaqueAlphaChannel);
+#endif
+
 	/*
 	 DiscreteAlphaChannel,                  CopyAlphaChannel,
 	 DisassociateAlphaChannel,              DeactivateAlphaChannel,