diff --git a/mozilla/base/src/nsString.cpp b/mozilla/base/src/nsString.cpp
index 1b2882d99e0..99a54b766ca 100644
--- a/mozilla/base/src/nsString.cpp
+++ b/mozilla/base/src/nsString.cpp
@@ -165,7 +165,7 @@ void nsString::EnsureCapacityFor(PRInt32 aNewLength)
     mCapacity=newCapacity;
     chartype* temp = new chartype[newCapacity+1];
     if (mLength > 0) {
-      nsCRT::memcpy(temp, mStr, mLength * sizeof(chartype));
+      nsCRT::memcpy(temp, mStr, mLength * sizeof(chartype) + sizeof(chartype));
     }
     if(mStr && (mStr!=kCommonEmptyBuffer))
       delete [] mStr;
@@ -1795,7 +1795,7 @@ void nsAutoString::EnsureCapacityFor(PRInt32 aNewLength) {
     mCapacity=size;
     chartype* temp = new chartype[mCapacity+1];
     if (mLength > 0) {
-      nsCRT::memcpy(temp, mStr, mLength * sizeof(chartype));
+      nsCRT::memcpy(temp, mStr, mLength * sizeof(chartype) + sizeof(chartype));
     }
     if ((mStr != mBuf) && (0 != mStr)) {
       delete [] mStr;
diff --git a/mozilla/base/src/nsString.h b/mozilla/base/src/nsString.h
index d5b82c8fa7d..912f5fb9f35 100644
--- a/mozilla/base/src/nsString.h
+++ b/mozilla/base/src/nsString.h
@@ -234,7 +234,7 @@ public:
 protected:
   virtual void EnsureCapacityFor(PRInt32 aNewLength);
 
-  PRUnichar mBuf[32];
+  chartype mBuf[32];
 };
 
 ostream& operator<<(ostream& os,nsAutoString& aString);
diff --git a/mozilla/string/obsolete/nsString.cpp b/mozilla/string/obsolete/nsString.cpp
index 1b2882d99e0..99a54b766ca 100644
--- a/mozilla/string/obsolete/nsString.cpp
+++ b/mozilla/string/obsolete/nsString.cpp
@@ -165,7 +165,7 @@ void nsString::EnsureCapacityFor(PRInt32 aNewLength)
     mCapacity=newCapacity;
     chartype* temp = new chartype[newCapacity+1];
     if (mLength > 0) {
-      nsCRT::memcpy(temp, mStr, mLength * sizeof(chartype));
+      nsCRT::memcpy(temp, mStr, mLength * sizeof(chartype) + sizeof(chartype));
     }
     if(mStr && (mStr!=kCommonEmptyBuffer))
       delete [] mStr;
@@ -1795,7 +1795,7 @@ void nsAutoString::EnsureCapacityFor(PRInt32 aNewLength) {
     mCapacity=size;
     chartype* temp = new chartype[mCapacity+1];
     if (mLength > 0) {
-      nsCRT::memcpy(temp, mStr, mLength * sizeof(chartype));
+      nsCRT::memcpy(temp, mStr, mLength * sizeof(chartype) + sizeof(chartype));
     }
     if ((mStr != mBuf) && (0 != mStr)) {
       delete [] mStr;
diff --git a/mozilla/string/obsolete/nsString.h b/mozilla/string/obsolete/nsString.h
index d5b82c8fa7d..912f5fb9f35 100644
--- a/mozilla/string/obsolete/nsString.h
+++ b/mozilla/string/obsolete/nsString.h
@@ -234,7 +234,7 @@ public:
 protected:
   virtual void EnsureCapacityFor(PRInt32 aNewLength);
 
-  PRUnichar mBuf[32];
+  chartype mBuf[32];
 };
 
 ostream& operator<<(ostream& os,nsAutoString& aString);
diff --git a/mozilla/xpcom/ds/nsString.cpp b/mozilla/xpcom/ds/nsString.cpp
index 1b2882d99e0..99a54b766ca 100644
--- a/mozilla/xpcom/ds/nsString.cpp
+++ b/mozilla/xpcom/ds/nsString.cpp
@@ -165,7 +165,7 @@ void nsString::EnsureCapacityFor(PRInt32 aNewLength)
     mCapacity=newCapacity;
     chartype* temp = new chartype[newCapacity+1];
     if (mLength > 0) {
-      nsCRT::memcpy(temp, mStr, mLength * sizeof(chartype));
+      nsCRT::memcpy(temp, mStr, mLength * sizeof(chartype) + sizeof(chartype));
     }
     if(mStr && (mStr!=kCommonEmptyBuffer))
       delete [] mStr;
@@ -1795,7 +1795,7 @@ void nsAutoString::EnsureCapacityFor(PRInt32 aNewLength) {
     mCapacity=size;
     chartype* temp = new chartype[mCapacity+1];
     if (mLength > 0) {
-      nsCRT::memcpy(temp, mStr, mLength * sizeof(chartype));
+      nsCRT::memcpy(temp, mStr, mLength * sizeof(chartype) + sizeof(chartype));
     }
     if ((mStr != mBuf) && (0 != mStr)) {
       delete [] mStr;
diff --git a/mozilla/xpcom/ds/nsString.h b/mozilla/xpcom/ds/nsString.h
index d5b82c8fa7d..912f5fb9f35 100644
--- a/mozilla/xpcom/ds/nsString.h
+++ b/mozilla/xpcom/ds/nsString.h
@@ -234,7 +234,7 @@ public:
 protected:
   virtual void EnsureCapacityFor(PRInt32 aNewLength);
 
-  PRUnichar mBuf[32];
+  chartype mBuf[32];
 };
 
 ostream& operator<<(ostream& os,nsAutoString& aString);
diff --git a/mozilla/xpcom/string/obsolete/nsString.cpp b/mozilla/xpcom/string/obsolete/nsString.cpp
index 1b2882d99e0..99a54b766ca 100644
--- a/mozilla/xpcom/string/obsolete/nsString.cpp
+++ b/mozilla/xpcom/string/obsolete/nsString.cpp
@@ -165,7 +165,7 @@ void nsString::EnsureCapacityFor(PRInt32 aNewLength)
     mCapacity=newCapacity;
     chartype* temp = new chartype[newCapacity+1];
     if (mLength > 0) {
-      nsCRT::memcpy(temp, mStr, mLength * sizeof(chartype));
+      nsCRT::memcpy(temp, mStr, mLength * sizeof(chartype) + sizeof(chartype));
     }
     if(mStr && (mStr!=kCommonEmptyBuffer))
       delete [] mStr;
@@ -1795,7 +1795,7 @@ void nsAutoString::EnsureCapacityFor(PRInt32 aNewLength) {
     mCapacity=size;
     chartype* temp = new chartype[mCapacity+1];
     if (mLength > 0) {
-      nsCRT::memcpy(temp, mStr, mLength * sizeof(chartype));
+      nsCRT::memcpy(temp, mStr, mLength * sizeof(chartype) + sizeof(chartype));
     }
     if ((mStr != mBuf) && (0 != mStr)) {
       delete [] mStr;
diff --git a/mozilla/xpcom/string/obsolete/nsString.h b/mozilla/xpcom/string/obsolete/nsString.h
index d5b82c8fa7d..912f5fb9f35 100644
--- a/mozilla/xpcom/string/obsolete/nsString.h
+++ b/mozilla/xpcom/string/obsolete/nsString.h
@@ -234,7 +234,7 @@ public:
 protected:
   virtual void EnsureCapacityFor(PRInt32 aNewLength);
 
-  PRUnichar mBuf[32];
+  chartype mBuf[32];
 };
 
 ostream& operator<<(ostream& os,nsAutoString& aString);