diff --git a/mozilla/js/src/jsdtoa.c b/mozilla/js/src/jsdtoa.c
index 4198cf19dbc..9f729fa8ab3 100644
--- a/mozilla/js/src/jsdtoa.c
+++ b/mozilla/js/src/jsdtoa.c
@@ -2665,7 +2665,7 @@ js_dtoa(double d, int mode, JSBool biasUp, int ndigits,
                     *s++ = '9';
                     goto roundoff;
                 }
-                *s++ = dig + 1;
+                *s++ = (char)dig + 1;
                 goto ret;
             }
             *s++ = (char)dig;
diff --git a/mozilla/js/src/jsstr.h b/mozilla/js/src/jsstr.h
index 94ebe97b942..acfb669df86 100644
--- a/mozilla/js/src/jsstr.h
+++ b/mozilla/js/src/jsstr.h
@@ -267,8 +267,12 @@ typedef enum JSCharType {
 #define JS_ISUPPER(c)   (JS_CTYPE(c) == JSCT_UPPERCASE_LETTER)
 #define JS_ISLOWER(c)   (JS_CTYPE(c) == JSCT_LOWERCASE_LETTER)
 
-#define JS_TOUPPER(c)   ((JS_CCODE(c) & 0x00100000) ? (c) - ((int32)JS_CCODE(c) >> 22) : (c))
-#define JS_TOLOWER(c)   ((JS_CCODE(c) & 0x00200000) ? (c) + ((int32)JS_CCODE(c) >> 22) : (c))
+#define JS_TOUPPER(c)   ((jschar) ((JS_CCODE(c) & 0x00100000)                 \
+                                   ? (c) - ((int32)JS_CCODE(c) >> 22)         \
+                                   : (c)))
+#define JS_TOLOWER(c)   ((jschar) ((JS_CCODE(c) & 0x00200000)                 \
+                                   ? (c) + ((int32)JS_CCODE(c) >> 22)         \
+                                   : (c)))
 
 #define JS_TOCTRL(c)    ((c) ^ 64)      /* XXX unsafe! requires uppercase c */