diff -Nurdb tcc-0.9.20/tcc.c tcc-0.9.20-dmg/tcc.c
--- tcc-0.9.20/tcc.c	2003-10-05 06:23:48.000000000 -0400
+++ tcc-0.9.20-dmg/tcc.c	2003-10-15 21:16:11.000000000 -0400
@@ -5394,6 +5394,16 @@
         force_charshort_cast(vtop->type.t);
     }
     
+    if (vtop->type.t & VT_BITFIELD) {
+        /* bitfields first get cast to ints */
+        gv(RC_INT);
+    }
+
+    if (type->t & VT_BITFIELD) {
+        /* can't cast *to* a bitfield */
+        type->t &= ~VT_BITFIELD;
+    }
+
     dbt = type->t & (VT_BTYPE | VT_UNSIGNED);
     sbt = vtop->type.t & (VT_BTYPE | VT_UNSIGNED);
 
diff -Nurdb tcc-0.9.20/tcctest.c tcc-0.9.20-dmg/tcctest.c
--- tcc-0.9.20/tcctest.c	2003-10-05 06:23:48.000000000 -0400
+++ tcc-0.9.20-dmg/tcctest.c	2003-10-15 21:30:34.000000000 -0400
@@ -1303,6 +1303,13 @@
     st1.f5++;
     printf("%d %d %d %d %d\n",
            st1.f1, st1.f2, st1.f3, st1.f4, st1.f5);
+
+    st1.f1 = 7;
+    if (st1.f1 == -1) printf("st1.f1 == -1\n");
+    else printf("st1.f1 != -1\n");
+    if (st1.f2 == -1) printf("st1.f2 == -1\n");
+    else printf("st1.f2 != -1\n");
+
 }
 
 #define FTEST(prefix, type, fmt)\