--- a/mfbt/SHA1.cpp
+++ b/mfbt/SHA1.cpp
@@ -94,50 +94,52 @@ SHA1Sum::SHA1Sum()
  */
 #define H2X 11 /* X[0] is H[11], and H[0] is X[-11] */
 #define W2X  6 /* X[0] is W[6],  and W[0] is X[-6]  */
 
 /*
  *  SHA: Add data to context.
  */
 void
-SHA1Sum::update(const uint8_t* dataIn, uint32_t len)
+SHA1Sum::update(const void* dataIn, uint32_t len)
 {
   MOZ_ASSERT(!mDone, "SHA1Sum can only be used to compute a single hash.");
 
+  const uint8_t* data = static_cast<const uint8_t*>(dataIn);
+
   if (len == 0)
     return;
 
   /* Accumulate the byte count. */
   unsigned int lenB = static_cast<unsigned int>(size) & 63U;
 
   size += len;
 
   /* Read the data into W and process blocks as they get full. */
   unsigned int togo;
   if (lenB > 0) {
     togo = 64U - lenB;
     if (len < togo)
       togo = len;
-    memcpy(u.b + lenB, dataIn, togo);
+    memcpy(u.b + lenB, data, togo);
     len -= togo;
-    dataIn += togo;
+    data += togo;
     lenB = (lenB + togo) & 63U;
     if (!lenB)
       shaCompress(&H[H2X], u.w);
   }
 
   while (len >= 64U) {
     len -= 64U;
-    shaCompress(&H[H2X], reinterpret_cast<const uint32_t*>(dataIn));
-    dataIn += 64U;
+    shaCompress(&H[H2X], reinterpret_cast<const uint32_t*>(data));
+    data += 64U;
   }
 
   if (len > 0)
-    memcpy(u.b, dataIn, len);
+    memcpy(u.b, data, len);
 }
 
 
 /*
  *  SHA: Generate hash value
  */
 void
 SHA1Sum::finish(SHA1Sum::Hash& hashOut)

--- a/mfbt/SHA1.h
+++ b/mfbt/SHA1.h
@@ -44,17 +44,17 @@ class SHA1Sum
 
   public:
     SHA1Sum();
 
     static const size_t HashSize = 20;
     typedef uint8_t Hash[HashSize];
 
     /* Add len bytes of dataIn to the data sequence being hashed. */
-    void update(const uint8_t* dataIn, uint32_t len);
+    void update(const void* dataIn, uint32_t len);
 
     /* Compute the final hash of all data into hashOut. */
     void finish(SHA1Sum::Hash& hashOut);
 };
 
 } /* namespace mozilla */
 
 #endif /* mozilla_SHA1_h_ */