diff --git a/lib/std/os/linux.zig b/lib/std/os/linux.zig
index 38e4abd197ba6c17245e7fe7038d7db0528ca395..16ae6587fb53f17e1ac6492431be4de75e7c1cbd 100644
--- a/lib/std/os/linux.zig
+++ b/lib/std/os/linux.zig
@@ -2774,7 +2774,7 @@ pub fn sigaddset(set: *sigset_t, sig: SIG) void {
 
 pub fn sigdelset(set: *sigset_t, sig: SIG) void {
     const index = sigset_bit_index(sig);
-    (set.*)[index.word] ^= index.mask;
+    (set.*)[index.word] &= ~index.mask;
 }
 
 pub fn sigismember(set: *const sigset_t, sig: SIG) bool {
diff --git a/lib/std/os/linux/test.zig b/lib/std/os/linux/test.zig
index 1a22e8f24a264d960040adde43a0070dc9d2fc96..552db88825d8c1a7d697b723cfc57f1d8a9abc72 100644
--- a/lib/std/os/linux/test.zig
+++ b/lib/std/os/linux/test.zig
@@ -159,6 +159,14 @@ test "sigset_t" {
     }
 }
 
+test "sigdelset" {
+    var set = linux.sigemptyset();
+
+    // Deleting an absent signal must leave it absent.
+    linux.sigdelset(&set, linux.SIG.USR1);
+    try expectEqual(false, linux.sigismember(&set, linux.SIG.USR1));
+}
+
 test "sigfillset" {
     // unlike the C library, all the signals are set in the kernel-level fillset
     const sigset = linux.sigfillset();