diff --git a/ChangeLog b/ChangeLog
index 0a37f6f1c..81d391916 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,15 @@
+2014-19-02 Paulo Andrade <pcpa@gnu.org>
+
+	* include/lightning/jit_aarch64.h, include/lightning/jit_arm.h,
+	include/lightning/jit_hppa.h, include/lightning/jit_ia64.h,
+	include/lightning/jit_mips.h, include/lightning/jit_ppc.h,
+	include/lightning/jit_s390x.h, include/lightning/jit_sparc.h,
+	include/lightning/jit_x86.h: Change jit_regset_t to an
+	unsigned type, to allow safe right shift.
+
+	* lib/lightning.c: Rewrite jit_regset_scan1 to allow easier
+	compiler optimization.
+
 2013-12-03 Paulo Andrade <pcpa@gnu.org>
 
 	* lib/jit_x86-x87.c: Correct wrong optimization when
diff --git a/include/lightning/jit_aarch64.h b/include/lightning/jit_aarch64.h
index b42f7093f..8e6a7eb26 100644
--- a/include/lightning/jit_aarch64.h
+++ b/include/lightning/jit_aarch64.h
@@ -90,6 +90,6 @@ typedef enum {
 #define JIT_NOREG		_NOREG
 } jit_reg_t;
 
-typedef jit_int64_t		jit_regset_t;
+typedef jit_uint64_t		jit_regset_t;
 
 #endif /* _jit_aarch64_h */
diff --git a/include/lightning/jit_arm.h b/include/lightning/jit_arm.h
index 1db759388..c8d2b14ce 100644
--- a/include/lightning/jit_arm.h
+++ b/include/lightning/jit_arm.h
@@ -123,7 +123,7 @@ typedef struct {
     jit_uint32_t ldrt_strt	: 1;
 } jit_cpu_t;
 
-typedef jit_int64_t		jit_regset_t;
+typedef jit_uint64_t		jit_regset_t;
 
 /*
  * Initialization
diff --git a/include/lightning/jit_hppa.h b/include/lightning/jit_hppa.h
index e7c5fe4e1..a24b2df23 100644
--- a/include/lightning/jit_hppa.h
+++ b/include/lightning/jit_hppa.h
@@ -133,6 +133,6 @@ typedef enum {
     _NOREG,
 } jit_reg_t;
 
-typedef jit_int64_t		jit_regset_t;
+typedef jit_uint64_t		jit_regset_t;
 
 #endif /* _jit_hppa */
diff --git a/include/lightning/jit_ia64.h b/include/lightning/jit_ia64.h
index 29f4189c0..12c61adbd 100644
--- a/include/lightning/jit_ia64.h
+++ b/include/lightning/jit_ia64.h
@@ -118,10 +118,10 @@ typedef enum {
 } jit_reg_t;
 
 typedef struct {
-    jit_int64_t		rl;
-    jit_int64_t		rh;
-    jit_int64_t		fl;
-    jit_int64_t		fh;
+    jit_uint64_t	rl;
+    jit_uint64_t	rh;
+    jit_uint64_t	fl;
+    jit_uint64_t	fh;
 } jit_regset_t;
 
 #endif /* _jit_ia64_h */
diff --git a/include/lightning/jit_mips.h b/include/lightning/jit_mips.h
index e361c220a..54e57db5a 100644
--- a/include/lightning/jit_mips.h
+++ b/include/lightning/jit_mips.h
@@ -119,6 +119,6 @@ typedef enum {
     _NOREG,
 } jit_reg_t;
 
-typedef jit_int64_t		jit_regset_t;
+typedef jit_uint64_t		jit_regset_t;
 
 #endif /* _jit_mips_h */
diff --git a/include/lightning/jit_ppc.h b/include/lightning/jit_ppc.h
index 4daf9de76..802189149 100644
--- a/include/lightning/jit_ppc.h
+++ b/include/lightning/jit_ppc.h
@@ -103,6 +103,6 @@ typedef enum {
 #define JIT_NOREG		_NOREG
 } jit_reg_t;
 
-typedef jit_int64_t		jit_regset_t;
+typedef jit_uint64_t		jit_regset_t;
 
 #endif /* _jit_ppc_h */
diff --git a/include/lightning/jit_s390x.h b/include/lightning/jit_s390x.h
index 072e72880..f84290c0d 100644
--- a/include/lightning/jit_s390x.h
+++ b/include/lightning/jit_s390x.h
@@ -67,6 +67,6 @@ typedef enum {
 #define JIT_NOREG		_NOREG
 } jit_reg_t;
 
-typedef jit_int32_t		jit_regset_t;
+typedef jit_uint32_t		jit_regset_t;
 
 #endif /* _jit_s390x_h */
diff --git a/include/lightning/jit_sparc.h b/include/lightning/jit_sparc.h
index 946d38284..63c7d7405 100644
--- a/include/lightning/jit_sparc.h
+++ b/include/lightning/jit_sparc.h
@@ -65,6 +65,6 @@ typedef enum {
     _NOREG,
 } jit_reg_t;
 
-typedef jit_int64_t		jit_regset_t;
+typedef jit_uint64_t		jit_regset_t;
 
 #endif /* _jit_sparc_h */
diff --git a/include/lightning/jit_x86.h b/include/lightning/jit_x86.h
index 3166f7170..5c85adb9b 100644
--- a/include/lightning/jit_x86.h
+++ b/include/lightning/jit_x86.h
@@ -139,9 +139,9 @@ typedef struct {
 } jit_cpu_t;
 
 #if __WORDSIZE == 32
-typedef jit_int32_t		jit_regset_t;
+typedef jit_uint32_t		jit_regset_t;
 #else
-typedef jit_int64_t		jit_regset_t;
+typedef jit_uint64_t		jit_regset_t;
 #endif
 
 /*
diff --git a/lib/lightning.c b/lib/lightning.c
index ebc76c114..de93e9fc5 100644
--- a/lib/lightning.c
+++ b/lib/lightning.c
@@ -496,10 +496,15 @@ jit_regset_scan1(jit_regset_t *set, jit_int32_t offset)
 unsigned long
 jit_regset_scan1(jit_regset_t *set, jit_int32_t offset)
 {
+    jit_regset_t       mask;
     assert(offset >= 0 && offset <= 63);
-    for (; offset < 64; offset++) {
-	if (*set & (1LL << offset))
-	    return (offset);
+    if ((mask = *set >> offset)) {
+	for (;;) {
+	    if (mask & 1)
+		return (offset);
+	    mask >>= 1;
+	    ++offset;
+	}
     }
     return (ULONG_MAX);
 }