diff --git a/src/dmd/backend/cod2.d b/src/dmd/backend/cod2.d
index 8438229353ea..2667e43ba1f6 100644
--- a/src/dmd/backend/cod2.d
+++ b/src/dmd/backend/cod2.d
@@ -2293,8 +2293,6 @@ void cdcond(ref CodeBuilder cdb,elem *e,regm_t *pretregs)
     regm_t psw = *pretregs & mPSW;               /* save PSW bit                 */
     const op1 = e1.Eoper;
     uint sz1 = tysize(e1.Ety);
-    uint rex = (I64 && sz1 == 8) ? REX_W : 0;
-    uint grex = rex << 16;
     uint jop = jmpopcode(e1);
 
     uint jop1 = jmpopcode(e21);
@@ -2341,6 +2339,10 @@ void cdcond(ref CodeBuilder cdb,elem *e,regm_t *pretregs)
         e22.Eoper == OPconst
        )
     {
+        uint sz = tysize(e.Ety);
+        uint rex = (I64 && sz == 8) ? REX_W : 0;
+        uint grex = rex << 16;
+
         regm_t retregs;
         targ_size_t v1,v2;
 
@@ -2357,7 +2359,7 @@ void cdcond(ref CodeBuilder cdb,elem *e,regm_t *pretregs)
                 retregs = BYTEREGS;
         }
 
-        cdcmp_flag = 1;
+        cdcmp_flag = 1 | rex;
         v1 = cast(targ_size_t)e21.EV.Vllong;
         v2 = cast(targ_size_t)e22.EV.Vllong;
         if (jop == JNC)
diff --git a/src/dmd/backend/cod4.d b/src/dmd/backend/cod4.d
index bf716e6ef74c..f1fa903b3cc7 100644
--- a/src/dmd/backend/cod4.d
+++ b/src/dmd/backend/cod4.d
@@ -3140,8 +3140,8 @@ L3:
             {
                 getregs(cdb,retregs);
                 genregs(cdb,0x19,reg,reg);     // SBB reg,reg
-                if (rex)
-                    code_orrex(cdb.last(), rex);
+                if (rex || flag & REX_W)
+                    code_orrex(cdb.last(), REX_W);
                 if (flag)
                 { }                                         // cdcond() will handle it
                 else if (jop == JNC)
diff --git a/test/runnable/mars1.d b/test/runnable/mars1.d
index 6b08c2bc6de9..de1c04d8b91d 100644
--- a/test/runnable/mars1.d
+++ b/test/runnable/mars1.d
@@ -638,14 +638,14 @@ void testfastdiv()
 
     static foreach (T; tuple!(int, long, uint, ulong))
     {{
-	T u = 10000;
-	T r;
-	static foreach (C; tuple!(10, 14, 14007, -10, -14, -14007))
-	{
-	    r = divC!C(u);     assert(r == u / (z + C));
-	    r = modC!C(u);     assert(r == u % (z + C));
-	    r = remquoC!C(u);  assert(r == ((u / (z + C) | (u % (z + C)))));
-	}
+        T u = 10000;
+        T r;
+        static foreach (C; tuple!(10, 14, 14007, -10, -14, -14007))
+        {
+            r = divC!C(u);     assert(r == u / (z + C));
+            r = modC!C(u);     assert(r == u % (z + C));
+            r = remquoC!C(u);  assert(r == ((u / (z + C) | (u % (z + C)))));
+        }
     }}
 }
 
@@ -2021,6 +2021,29 @@ void testrolror()
 
 ////////////////////////////////////////////////////////////////////////
 
+// https://issues.dlang.org/show_bug.cgi?id=20162
+
+void test20162()
+{
+    static long f(long a)
+    {
+         assert(a == -1L);
+         return a;
+    }
+
+    foreach (i; 1 .. 2)
+    {
+        foreach (j; 0 .. 2)
+        {
+            printf("%d %d %llx\n", i,
+              ((i != 0) ? -1 : +1),
+              f((i != 0) ? -1 : +1));
+        }
+    }
+}
+
+////////////////////////////////////////////////////////////////////////
+
 // Some tests for OPmemcpy
 
 enum N = 128;
@@ -2205,6 +2228,7 @@ int main()
     test7();
     testbyteswap();
     testrolror();
+    test20162();
     testmemcpy();
     testMulLea();
     testMulAssPair();