diff --git a/gcc/fold-const.cc b/gcc/fold-const.cc
index c4e181d3594a20b63f77f37733ddbc7c9d43f53d..7ebcac3066668d6c5b5709c8825e59638174e1d2 100644
--- a/gcc/fold-const.cc
+++ b/gcc/fold-const.cc
@@ -14258,7 +14258,7 @@ multiple_of_p (tree type, const_tree top, const_tree bottom, bool nowrap)
 	      && TREE_CODE (op2) == INTEGER_CST
 	      && integer_pow2p (bottom)
 	      && wi::multiple_of_p (wi::to_widest (op2),
-				    wi::to_widest (bottom), UNSIGNED))
+				    wi::to_widest (bottom), SIGNED))
 	    return 1;
 
 	  op1 = gimple_assign_rhs1 (stmt);
diff --git a/gcc/testsuite/gcc.dg/pr112733.c b/gcc/testsuite/gcc.dg/pr112733.c
new file mode 100644
index 0000000000000000000000000000000000000000..d6f99f76077515eb8c8cbbcbf9169b247526cd10
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/pr112733.c
@@ -0,0 +1,16 @@
+/* PR middle-end/112733 */
+/* { dg-do compile } */
+/* { dg-options "-O2" } */
+
+signed char a, c;
+short b;
+
+void
+foo (void)
+{
+  signed char *e = &a;
+  c = foo != 0;
+  *e &= c;
+  for (; b; --b)
+    *e &= -128;
+}