diff --git a/source/common/ucnv.c b/source/common/ucnv.c
index fb4bab88a78..57519279751 100644
--- a/source/common/ucnv.c
+++ b/source/common/ucnv.c
@@ -711,6 +711,7 @@ int32_t   ucnv_fromUChars (const UConverter * converter,
   int32_t mySourceLength = 0;
   UConverter myConverter;
   char *myTarget = target;
+  char *myTarget_limit;
   int32_t targetCapacity = 0;
 
   if (U_FAILURE (*err))
@@ -741,6 +742,10 @@ int32_t   ucnv_fromUChars (const UConverter * converter,
     }
 
   mySource_limit = mySource + mySourceLength;
+  myTarget_limit = target + targetSize;
+
+  if(myTarget_limit < target)
+    myTarget_limit = U_MAX_PTR; /* ptr wrapped */
 
   if (targetSize > 0)
     {
@@ -771,6 +776,10 @@ int32_t   ucnv_fromUChars (const UConverter * converter,
       char *target2_alias = target2;
       const char *target2_limit = target2 + CHUNK_SIZE;
 
+
+      if(target2_limit < target2)
+	target2_limit = U_MAX_PTR; /* wrapped around */
+
       /*We use a stack allocated buffer around which we loop
        *(in case the output is greater than CHUNK_SIZE)
        */
@@ -812,6 +821,7 @@ int32_t ucnv_toUChars (const UConverter * converter,
   const char *mySource_limit = source + sourceSize;
   UConverter myConverter;
   UChar *myTarget = target;
+  UChar *myTarget_limit;
   int32_t targetCapacity;
 
   if (U_FAILURE (*err))
@@ -844,6 +854,11 @@ int32_t ucnv_toUChars (const UConverter * converter,
   /*Removes all state info on the UConverter */
   ucnv_reset (&myConverter);
 
+  myTarget_limit = target + targetSize - 1;
+
+  if(myTarget_limit < target) /* wrapped */
+    myTarget_limit = U_MAX_PTR;
+
 
   /*Not in pure pre-flight mode */
   if (targetSize > 0)
@@ -851,7 +866,7 @@ int32_t ucnv_toUChars (const UConverter * converter,
 
       ucnv_toUnicode (&myConverter,
 		      &myTarget,
-		      target + targetSize - 1,	  /*Save a spot for the Null terminator */
+		      myTarget_limit,	  /*Save a spot for the Null terminator */
 		      &mySource,
 		      mySource_limit,
 		      NULL,
diff --git a/source/common/unistr.cpp b/source/common/unistr.cpp
index d0490681887..b77cd7daacc 100644
--- a/source/common/unistr.cpp
+++ b/source/common/unistr.cpp
@@ -759,6 +759,7 @@ UnicodeString::extract(UTextOffset start,
   const UChar *mySource    = getArrayStart() + start;
   const UChar *mySourceEnd = mySource + length;
   char *myTarget           = dst;
+  char *myTargetLimit;
   UErrorCode status        = U_ZERO_ERROR;
   int32_t arraySize        = 0x0FFFFFFF;
 
@@ -781,6 +782,11 @@ UnicodeString::extract(UTextOffset start,
     return 0;
   }
 
+  myTargetLimit = myTarget + arraySize;
+
+  if(myTargetLimit < myTarget)  /* ptr wrapped around: pin to U_MAX_PTR */
+    myTargetLimit = U_MAX_PTR; 
+
   // perform the conversion
   // there is no loop here since we assume the buffer is large enough
 
diff --git a/source/common/ustring.c b/source/common/ustring.c
index eefbee9bc35..66c69f0a48f 100644
--- a/source/common/ustring.c
+++ b/source/common/ustring.c
@@ -27,7 +27,7 @@
 static UConverter* _defaultConverter = NULL;
 static UErrorCode gErr = U_ZERO_ERROR;
 
-#define MAX_STRLEN 0x00FFFFFF
+#define MAX_STRLEN 0x0FFFFFFF
 
 /*Lazy evaluating macro for the default converter*/
 #define defaultConverter (_defaultConverter==NULL)?_defaultConverter=ucnv_open(NULL, &gErr):_defaultConverter
diff --git a/source/common/utypes.h b/source/common/utypes.h
index 72412788022..010047edab5 100644
--- a/source/common/utypes.h
+++ b/source/common/utypes.h
@@ -135,6 +135,9 @@ typedef uint16_t UChar;
 #endif
 #endif
 
+/* Maximum value of a (void*) - use to indicate the limit of
+   an 'infinite' buffer.  */
+#define U_MAX_PTR ((void*)-1)
 
 /*===========================================================================*/
 /* Calendar/TimeZone data types                                              */