diff --git a/libtransmission/rpcimpl.c b/libtransmission/rpcimpl.c
index 780ee706f..af9a0a4a0 100644
--- a/libtransmission/rpcimpl.c
+++ b/libtransmission/rpcimpl.c
@@ -1040,29 +1040,6 @@ tr_rpc_request_exec_json( tr_session            * session,
         tr_bencFree( &top );
 }
 
-static void
-addToken( tr_benc *    list,
-          const char * token,
-          size_t       len )
-{
-    char *       p;
-    const char * end = token + len;
-    const long   a = strtol( token, &p, 10 );
-
-    if( p == end )
-        tr_bencListAddInt( list, a );
-    else if( *p == '-' && isdigit( p[1] ) )
-    {
-        const long b = strtol( p + 1, &p, 10 );
-        if( ( p == end ) && ( b > a ) )
-        {
-            long i;
-            for( i = a; i <= b; ++i )
-                tr_bencListAddInt( list, i );
-        }
-    }
-}
-
 /**
  * Munge the URI into a usable form.
  *
@@ -1074,49 +1051,25 @@ addToken( tr_benc *    list,
  */
 void
 tr_rpc_parse_list_str( tr_benc     * setme,
-                       const char  * str_in,
+                       const char  * str,
                        int           len )
 
 {
-    char *       str = tr_strndup( str_in, len );
-    int          isNum;
-    int          isNumList;
-    int          commaCount;
-    const char * walk;
+    int valueCount;
+    int * values = tr_parseNumberRange( str, len, &valueCount );
 
-    isNum = 1;
-    isNumList = 1;
-    commaCount = 0;
-    walk = str;
-    for( ; *walk && ( isNumList || isNum ); ++walk )
-    {
-        if( isNumList ) isNumList = *walk == '-' || isdigit( *walk )
-                                    || *walk == ',';
-        if( isNum     ) isNum     = *walk == '-' || isdigit( *walk );
-        if( *walk == ',' ) ++commaCount;
-    }
-
-    if( isNum )
-        tr_bencInitInt( setme, strtol( str, NULL, 10 ) );
-    else if( !isNumList )
+    if( valueCount == 0 )
         tr_bencInitStr( setme, str, len );
-    else
-    {
-        tr_bencInitList( setme, commaCount + 1 );
-        walk = str;
-        while( *walk )
-        {
-            const char * p = strchr( walk, ',' );
-            if( !p )
-                p = walk + strlen( walk );
-            addToken( setme, walk, p - walk );
-            if( *p != ',' )
-                break;
-            walk = p + 1;
-        }
+    else if( valueCount == 1 )
+        tr_bencInitInt( setme, values[0] );
+    else {
+        int i;
+        tr_bencInitList( setme, valueCount );
+        for( i=0; i<valueCount; ++i )
+            tr_bencListAddInt( setme, values[i] );
     }
 
-    tr_free( str );
+    tr_free( values );
 }
 
 void
diff --git a/libtransmission/utils-test.c b/libtransmission/utils-test.c
index 048fcf334..d893697e6 100644
--- a/libtransmission/utils-test.c
+++ b/libtransmission/utils-test.c
@@ -185,6 +185,46 @@ test_utf8( void )
     return 0;
 }
 
+static int
+test_numbers( void )
+{
+    int i;
+    int count;
+    int * numbers;
+
+    numbers = tr_parseNumberRange( "1-10,13,16-19", -1, &count );
+    check( count == 15 );
+    check( numbers != NULL );
+    check( numbers[0] == 1 );
+    check( numbers[5] == 6 );
+    check( numbers[9] == 10 );
+    check( numbers[10] == 13 );
+    check( numbers[11] == 16 );
+    check( numbers[14] == 19 );
+    tr_free( numbers );
+
+    numbers = tr_parseNumberRange( "1-5,3-7,2-6", -1, &count );
+    check( count == 7 );
+    check( numbers != NULL );
+    for( i=0; i<count; ++i )
+        check( numbers[i] == i+1 );
+    tr_free( numbers );
+
+    numbers = tr_parseNumberRange( "1-Hello", -1, &count );
+    check( count == 0 );
+    check( numbers == NULL );
+
+    numbers = tr_parseNumberRange( "1-", -1, &count );
+    check( count == 0 );
+    check( numbers == NULL );
+
+    numbers = tr_parseNumberRange( "Hello", -1, &count );
+    check( count == 0 );
+    check( numbers == NULL );
+
+    return 0;
+}
+
 int
 main( void )
 {
@@ -211,6 +251,8 @@ main( void )
         return i;
     if( ( i = test_utf8( ) ) )
         return i;
+    if( ( i = test_numbers( ) ) )
+        return i;
 
     /* test that tr_cryptoRandInt() stays in-bounds */
     for( i = 0; i < 100000; ++i )
diff --git a/libtransmission/utils.c b/libtransmission/utils.c
index ee8ecffd1..451046c75 100644
--- a/libtransmission/utils.c
+++ b/libtransmission/utils.c
@@ -1378,3 +1378,138 @@ tr_utf8clean( const char * str, int max_len, tr_bool * err )
     evbuffer_free( buf );
     return ret;
 }
+
+/***
+****
+***/
+
+struct number_range
+{
+    int low;
+    int high;
+};
+
+/**
+ * This should be a single number (ex. "6") or a range (ex. "6-9").
+ * Anything else is an error and will return failure.
+ */
+static tr_bool
+parseNumberSection( const char * str, int len, struct number_range * setme )
+{
+    long a, b;
+    tr_bool success;
+    char * end;
+    const int error = errno;
+    char * tmp = tr_strndup( str, len );
+
+    errno = 0;
+    a = strtol( tmp, &end, 10 );
+    if( errno || ( end == tmp ) ) {
+        success = FALSE;
+    } else if( *end != '-' ) {
+        b = a;
+        success = TRUE;
+    } else {
+        const char * pch = end + 1;
+        b = strtol( pch, &end, 10 );
+        if( errno || ( pch == end ) )
+            success = FALSE;
+        else if( *end ) /* trailing data */
+            success = FALSE;
+        else
+            success = TRUE;
+    }
+    tr_free( tmp );
+
+    setme->low = MIN( a, b );
+    setme->high = MAX( a, b );
+
+    errno = error;
+    return success;
+}
+
+static int
+compareInt( const void * va, const void * vb )
+{
+    const int a = *(const int *)va;
+    const int b = *(const int *)vb;
+    return a - b;
+}
+
+/**
+ * Given a string like "1-4" or "1-4,6,9,14-51", this allocates and returns an
+ * array of setmeCount ints of all the values in the array.
+ * For example, "5-8" will return [ 5, 6, 7, 8 ] and setmeCount will be 4.
+ * It's the caller's responsibility to call tr_free() on the returned array. 
+ * If a fragment of the string can't be parsed, NULL is returned.
+ */
+int*
+tr_parseNumberRange( const char * str_in, int len, int * setmeCount )
+{
+    int n = 0;
+    int * uniq = NULL;
+    char * str = tr_strndup( str_in, len );
+    const char * walk;
+    tr_list * ranges = NULL;
+    tr_bool success = TRUE;
+
+    walk = str;
+    while( walk && *walk && success ) {
+        struct number_range range;
+        const char * pch = strchr( walk, ',' );
+        if( pch ) {
+            success = parseNumberSection( walk, pch-walk, &range );
+            walk = pch + 1;
+        } else {
+            success = parseNumberSection( walk, strlen( walk ), &range );
+            walk += strlen( walk );
+        }
+        if( success )
+            tr_list_append( &ranges, tr_memdup( &range, sizeof( struct number_range ) ) );
+    }
+
+    if( !success )
+    {
+        *setmeCount = 0;
+        uniq = NULL;
+    }
+    else
+    {
+        int i;
+        int n2;
+        tr_list * l;
+        int * sorted = NULL;
+
+        /* build a sorted number array */
+        n = n2 = 0;
+        for( l=ranges; l!=NULL; l=l->next ) {
+            const struct number_range * r = l->data;
+            n += r->high + 1 - r->low;
+        }
+        sorted = tr_new( int, n );
+        for( l=ranges; l!=NULL; l=l->next ) {
+            const struct number_range * r = l->data;
+            int i;
+            for( i=r->low; i<=r->high; ++i )
+                sorted[n2++] = i;
+        }
+        qsort( sorted, n, sizeof( int ), compareInt );
+        assert( n == n2 );
+
+        /* remove duplicates */
+        uniq = tr_new( int, n );
+        for( i=n=0; i<n2; ++i )
+            if( !n || uniq[n-1] != sorted[i] )
+                uniq[n++] = sorted[i];
+
+        tr_free( sorted );
+    }
+
+    /* cleanup */
+    tr_list_free( &ranges, tr_free );
+    tr_free( str );
+
+    /* return the result */
+    *setmeCount = n;
+    return uniq;
+}
diff --git a/libtransmission/utils.h b/libtransmission/utils.h
index b32fd66a0..ddcd8c1d5 100644
--- a/libtransmission/utils.h
+++ b/libtransmission/utils.h
@@ -451,6 +451,8 @@ static TR_INLINE tr_bool tr_bitfieldHas( const tr_bitfield * b, size_t nth )
 
 double tr_getRatio( double numerator, double denominator );
 
+int* tr_parseNumberRange( const char * str, int str_len, int * setmeCount );
+
 
 int tr_ptr2int( void* );