diff --git a/ObsoleteFiles.inc b/ObsoleteFiles.inc
index 2f71a267e627..2492bf4731ee 100644
--- a/ObsoleteFiles.inc
+++ b/ObsoleteFiles.inc
@@ -52,6 +52,16 @@
 #   xargs -n1 | sort | uniq -d;
 # done
 
+# 20230320: case-sensitive conflicts removed
+OLD_FILES+=usr/tests/bin/pkill/pgrep-F_test
+OLD_FILES+=usr/tests/bin/pkill/pgrep-LF_test
+OLD_FILES+=usr/tests/bin/pkill/pgrep-P_test
+OLD_FILES+=usr/tests/bin/pkill/pgrep-U_test
+OLD_FILES+=usr/tests/bin/pkill/pkill-F_test
+OLD_FILES+=usr/tests/bin/pkill/pkill-LF_test
+OLD_FILES+=usr/tests/bin/pkill/pkill-P_test
+OLD_FILES+=usr/tests/bin/pkill/pkill-U_test
+
 # 20230309: remove remaining ATM support
 OLD_FILES+=usr/bin/sscop
 OLD_FILES+=usr/include/netnatm/addr.h
diff --git a/bin/pkill/tests/Makefile b/bin/pkill/tests/Makefile
index 9bf448bb2460..66a1d655b764 100644
--- a/bin/pkill/tests/Makefile
+++ b/bin/pkill/tests/Makefile
@@ -7,10 +7,10 @@ PACKAGE=	tests
 PROGS+=		spin_helper
 BINDIR=		${TESTSDIR}
 
-TAP_TESTS_SH=			pgrep-F_test
-TAP_TESTS_SH+=			pgrep-LF_test
-TAP_TESTS_SH+=			pgrep-P_test
-TAP_TESTS_SH+=			pgrep-U_test
+TAP_TESTS_SH=			pgrep-_f_test
+TAP_TESTS_SH+=			pgrep-_lf_test
+TAP_TESTS_SH+=			pgrep-_p_test
+TAP_TESTS_SH+=			pgrep-_u_test
 TAP_TESTS_SH+=			pgrep-_g_test
 TAP_TESTS_SH+=			pgrep-_s_test
 TAP_TESTS_SH+=			pgrep-g_test
@@ -27,10 +27,10 @@ TAP_TESTS_SH+=			pgrep-s_test
 TAP_TESTS_SH+=			pgrep-t_test
 TAP_TESTS_SH+=			pgrep-v_test
 TAP_TESTS_SH+=			pgrep-x_test
-TAP_TESTS_SH+=			pkill-F_test
-TAP_TESTS_SH+=			pkill-LF_test
-TAP_TESTS_SH+=			pkill-P_test
-TAP_TESTS_SH+=			pkill-U_test
+TAP_TESTS_SH+=			pkill-_f_test
+TAP_TESTS_SH+=			pkill-_lf_test
+TAP_TESTS_SH+=			pkill-_p_test
+TAP_TESTS_SH+=			pkill-_u_test
 TAP_TESTS_SH+=			pkill-_g_test
 TAP_TESTS_SH+=			pkill-g_test
 TAP_TESTS_SH+=			pkill-i_test
diff --git a/bin/pkill/tests/pgrep-F_test.sh b/bin/pkill/tests/pgrep-_f_test.sh
similarity index 100%
rename from bin/pkill/tests/pgrep-F_test.sh
rename to bin/pkill/tests/pgrep-_f_test.sh
diff --git a/bin/pkill/tests/pgrep-LF_test.sh b/bin/pkill/tests/pgrep-_lf_test.sh
similarity index 100%
rename from bin/pkill/tests/pgrep-LF_test.sh
rename to bin/pkill/tests/pgrep-_lf_test.sh
diff --git a/bin/pkill/tests/pgrep-P_test.sh b/bin/pkill/tests/pgrep-_p_test.sh
similarity index 100%
rename from bin/pkill/tests/pgrep-P_test.sh
rename to bin/pkill/tests/pgrep-_p_test.sh
diff --git a/bin/pkill/tests/pgrep-U_test.sh b/bin/pkill/tests/pgrep-_u_test.sh
similarity index 100%
rename from bin/pkill/tests/pgrep-U_test.sh
rename to bin/pkill/tests/pgrep-_u_test.sh
diff --git a/bin/pkill/tests/pkill-F_test.sh b/bin/pkill/tests/pkill-_f_test.sh
similarity index 100%
rename from bin/pkill/tests/pkill-F_test.sh
rename to bin/pkill/tests/pkill-_f_test.sh
diff --git a/bin/pkill/tests/pkill-LF_test.sh b/bin/pkill/tests/pkill-_lf_test.sh
similarity index 100%
rename from bin/pkill/tests/pkill-LF_test.sh
rename to bin/pkill/tests/pkill-_lf_test.sh
diff --git a/bin/pkill/tests/pkill-P_test.sh b/bin/pkill/tests/pkill-_p_test.sh
similarity index 100%
rename from bin/pkill/tests/pkill-P_test.sh
rename to bin/pkill/tests/pkill-_p_test.sh
diff --git a/bin/pkill/tests/pkill-U_test.sh b/bin/pkill/tests/pkill-_u_test.sh
similarity index 100%
rename from bin/pkill/tests/pkill-U_test.sh
rename to bin/pkill/tests/pkill-_u_test.sh