diff --git a/priv/guest_s390_helpers.c b/priv/guest_s390_helpers.c
index cf223c4..622cdcc 100644
--- a/priv/guest_s390_helpers.c
+++ b/priv/guest_s390_helpers.c
@@ -1566,7 +1566,7 @@
 
    case S390_CC_OP_TEST_UNDER_MASK_16: {
       /* Create a TMLL insn with the mask as given by cc_dep2 */
-      UInt insn  = (0xA701 << 16) | cc_dep2;
+      UInt insn  = (0xA701u << 16) | cc_dep2;
       UInt value = cc_dep1;
 
       __asm__ volatile (
diff --git a/priv/guest_s390_toIR.c b/priv/guest_s390_toIR.c
index e066d10..96d4432 100644
--- a/priv/guest_s390_toIR.c
+++ b/priv/guest_s390_toIR.c
@@ -94,15 +94,6 @@
 /*--- Helpers for constructing IR.                         ---*/
 /*------------------------------------------------------------*/
 
-/* Sign extend a value with the given number of bits. This is a
-   macro because it allows us to overload the type of the value.
-   Note that VALUE must have a signed type! */
-#undef sign_extend
-#define sign_extend(value,num_bits) \
-(((value) << (sizeof(__typeof__(value)) * 8 - (num_bits))) >> \
- (sizeof(__typeof__(value)) * 8 - (num_bits)))
-
-
 /* Add a statement to the current irsb. */
 static __inline__ void
 stmt(IRStmt *st)
diff --git a/priv/host_s390_defs.c b/priv/host_s390_defs.c
index 1746baa..ea2f718 100644
--- a/priv/host_s390_defs.c
+++ b/priv/host_s390_defs.c
@@ -185,7 +185,8 @@
 static __inline__ Bool
 fits_signed_20bit(Int value)
 {
-   return ((value << 12) >> 12) == value;
+   UInt uval = value;
+   return ((Int)(uval << 12) >> 12) == value;
 }
 
 
@@ -4725,36 +4726,36 @@
 static __inline__ Bool
 uint_fits_signed_16bit(UInt val)
 {
-   Int v = val & 0xFFFFu;
+   UInt v = val & 0xFFFFu;
 
    /* sign extend */
-   v = (v << 16) >> 16;
+   v = (Int)(v << 16) >> 16;
 
-   return val == (UInt)v;
+   return val == v;
 }
 
 
 static __inline__ Bool
 ulong_fits_signed_16bit(ULong val)
 {
-   Long v = val & 0xFFFFu;
+   ULong v = val & 0xFFFFu;
 
    /* sign extend */
-   v = (v << 48) >> 48;
+   v = (Long)(v << 48) >> 48;
 
-   return val == (ULong)v;
+   return val == v;
 }
 
 
 static __inline__ Bool
 ulong_fits_signed_32bit(ULong val)
 {
-   Long v = val & 0xFFFFFFFFu;
+   ULong v = val & 0xFFFFFFFFu;
 
    /* sign extend */
-   v = (v << 32) >> 32;
+   v = (Long)(v << 32) >> 32;
 
-   return val == (ULong)v;
+   return val == v;
 }
 
 
diff --git a/priv/host_s390_isel.c b/priv/host_s390_isel.c
index e8e6fc8..f7af2a9 100644
--- a/priv/host_s390_isel.c
+++ b/priv/host_s390_isel.c
@@ -268,22 +268,22 @@
 static __inline__ Bool
 ulong_fits_signed_20bit(ULong val)
 {
-   Long v = val & 0xFFFFFu;
+   ULong v = val & 0xFFFFFu;
 
-   v = (v << 44) >> 44;  /* sign extend */
+   v = (Long)(v << 44) >> 44;  /* sign extend */
 
-   return val == (ULong)v;
+   return val == v;
 }
 
 
 static __inline__ Bool
 ulong_fits_signed_8bit(ULong val)
 {
-   Long v = val & 0xFFu;
+   ULong v = val & 0xFFu;
 
-   v = (v << 56) >> 56;  /* sign extend */
+   v = (Long)(v << 56) >> 56;  /* sign extend */
 
-   return val == (ULong)v;
+   return val == v;
 }
 
 /* EXPR is an expression that is used as an address. Return an s390_amode
@@ -463,13 +463,13 @@
 static ULong
 get_const_value_as_ulong(const IRConst *con)
 {
-   Long value;
+   ULong value;
 
    switch (con->tag) {
-   case Ico_U1:  value = con->Ico.U1;  return (ULong) ((value << 63) >> 63);
-   case Ico_U8:  value = con->Ico.U8;  return (ULong) ((value << 56) >> 56);
-   case Ico_U16: value = con->Ico.U16; return (ULong) ((value << 48) >> 48);
-   case Ico_U32: value = con->Ico.U32; return (ULong) ((value << 32) >> 32);
+   case Ico_U1:  value = con->Ico.U1;  return ((Long)(value << 63) >> 63);
+   case Ico_U8:  value = con->Ico.U8;  return ((Long)(value << 56) >> 56);
+   case Ico_U16: value = con->Ico.U16; return ((Long)(value << 48) >> 48);
+   case Ico_U32: value = con->Ico.U32; return ((Long)(value << 32) >> 32);
    case Ico_U64: return con->Ico.U64;
    default:
       vpanic("get_const_value_as_ulong");
diff --git a/priv/s390_disasm.c b/priv/s390_disasm.c
index 6a52409..95cf1f7 100644
--- a/priv/s390_disasm.c
+++ b/priv/s390_disasm.c
@@ -246,7 +246,7 @@
 dxb_operand(HChar *p, UInt d, UInt x, UInt b, Bool displacement_is_signed)
 {
    if (displacement_is_signed) {
-      Int displ = ((Int)d << 12) >> 12;  /* sign extend */
+      Int displ = (Int)(d << 12) >> 12;  /* sign extend */
 
       p += vex_sprintf(p, "%d", displ);
    } else {
@@ -399,15 +399,15 @@
          break;
 
       case S390_ARG_PCREL: {
-         Int offset = (Int)(va_arg(args, UInt));
+         Long offset = va_arg(args, Int);
 
          /* Convert # halfwords to # bytes */
          offset <<= 1;
 
          if (offset < 0) {
-            p += vex_sprintf(p, ".%d", offset);
+            p += vex_sprintf(p, ".%lld", offset);
          } else {
-            p += vex_sprintf(p, ".+%u", offset);
+            p += vex_sprintf(p, ".+%lld", offset);
          }
          break;
       }