diff --git a/dev-util/rtc-testbench/rtc-testbench-5.4.ebuild b/dev-util/rtc-testbench/rtc-testbench-5.4.ebuild
index 132b137a38..ed4587eb25 100644
--- a/dev-util/rtc-testbench/rtc-testbench-5.4.ebuild
+++ b/dev-util/rtc-testbench/rtc-testbench-5.4.ebuild
@@ -3,7 +3,7 @@
 
 EAPI=8
 
-LLVM_COMPAT=( {15..20} )
+LLVM_COMPAT=( {15..21} )
 PYTHON_COMPAT=( python3_{12..14} )
 
 inherit cmake python-single-r1 llvm-r2