diff --git a/krita.changes b/krita.changes
index ffec39f..51f08c7 100644
--- a/krita.changes
+++ b/krita.changes
@@ -1,3 +1,14 @@
+-------------------------------------------------------------------
+Tue Mar  2 15:57:09 UTC 2021 - Ben Greiner <code@bnavigator.de>
+
+- BuildConflict on python3-sip-devel >= 6 because the build expects
+  the sip5 executable (or even older sip from SIP v4), which was
+  removed in SIP v6. A simple BuildRequire python3-sip-devel < 6
+  would result in a parallel install of SIPv4 and SIPv6, which do
+  not conflict per se.  Because CMake sees the SIPv6 modules, it
+  assumes sip5 to be present, does not look for the old sip command
+  and fails.
+
 -------------------------------------------------------------------
 Tue Jan 19 12:28:32 UTC 2021 - Wolfgang Bauer <wbauer@tmo.at>
 
diff --git a/krita.spec b/krita.spec
index 802fde7..13e3039 100644
--- a/krita.spec
+++ b/krita.spec
@@ -57,8 +57,16 @@ BuildRequires:  libtiff-devel
 BuildRequires:  openjpeg2-devel
 BuildRequires:  perl
 BuildRequires:  pkgconfig
+# SECTION python build requirements
 BuildRequires:  python3-devel
 BuildRequires:  python3-qt5-devel
+# Krita's CMake requires the command `sip5` from SIP v5 or `sip` from SIP v4.
+# Neither is available in SIP v6. A simple sip-devel < 6 build requirement would
+# install a non-conflicting SIP v4 in parallel to v6 pulled in by qt5-devel.
+# But then CMake does not find the old sip executable.
+BuildConflicts: python3-sip-devel >= 6
+BuildRequires:  python3-sip-devel
+# /SECTION
 BuildRequires:  update-desktop-files
 BuildRequires:  zlib-devel
 BuildRequires:  cmake(KF5Archive)