diff --git a/tools/testing/selftests/net/toeplitz.c b/tools/testing/selftests/net/toeplitz.c
index 8ce96028341d..09771d61ea34 100644
--- a/tools/testing/selftests/net/toeplitz.c
+++ b/tools/testing/selftests/net/toeplitz.c
@@ -471,8 +471,8 @@ static void parse_rps_bitmap(const char *arg)
 
 	bitmap = strtoul(arg, NULL, 0);
 
-	if (bitmap & ~(RPS_MAX_CPUS - 1))
-		error(1, 0, "rps bitmap 0x%lx out of bounds 0..%lu",
+	if (bitmap & ~((1UL << RPS_MAX_CPUS) - 1))
+		error(1, 0, "rps bitmap 0x%lx out of bounds, max cpu %lu",
 		      bitmap, RPS_MAX_CPUS - 1);
 
 	for (i = 0; i < RPS_MAX_CPUS; i++)