diff --git a/eclass/toolchain.eclass b/eclass/toolchain.eclass
index dad4ae3d19722..096cc3018af5a 100644
--- a/eclass/toolchain.eclass
+++ b/eclass/toolchain.eclass
@@ -1478,7 +1478,8 @@ gcc_do_filter_flags() {
 		FFLAGS=${CFLAGS}
 		FCFLAGS=${CFLAGS}
 
-		local VAR="CFLAGS_"${CTARGET//-/_}
+		# "hppa2.0-unknown-linux-gnu" -> hppa2_0_unknown_linux_gnu
+		local VAR="CFLAGS_"${CTARGET//[-.]/_}
 		CXXFLAGS=${!VAR}
 	fi