diff --git a/lib/std/mem.zig b/lib/std/mem.zig
index eb3937034625c3b83a83571f767352bc07cd5635..3f24091946f8abe7613764ad3a0f2c14e70b1cad 100644
--- a/lib/std/mem.zig
+++ b/lib/std/mem.zig
@@ -1187,6 +1187,7 @@ pub fn indexOfScalarPos(comptime T: type, slice: []const T, start_index: usize,
 
     var i: usize = start_index;
     if (backend_supports_vectors and
+        !std.debug.inValgrind() and // https://github.com/ziglang/zig/issues/17717
         !@inComptime() and
         (@typeInfo(T) == .Int or @typeInfo(T) == .Float) and std.math.isPowerOfTwo(@bitSizeOf(T)))
     {