diff --git a/src/line_buffer.cc b/src/line_buffer.cc
index 3362b7ab..90552d55 100644
--- a/src/line_buffer.cc
+++ b/src/line_buffer.cc
@@ -222,23 +222,24 @@ throw (error)
 void line_buffer::resize_buffer(size_t new_max)
 throw (error)
 {
-    char *tmp, *old;
-
     require(this->lb_bz_file || this->lb_gz_file ||
         new_max <= MAX_LINE_BUFFER_SIZE);
 
-    /* Still need more space, try a realloc. */
-    old = this->lb_buffer.release();
-    this->lb_share_manager.invalidate_refs();
-    tmp = (char *)realloc(old, new_max);
-    if (tmp != NULL) {
-        this->lb_buffer     = tmp;
-        this->lb_buffer_max = new_max;
-    }
-    else {
-        this->lb_buffer = old;
+    if  (new_max > this->lb_buffer_max) {
+        char *tmp, *old;
 
-        throw error(ENOMEM);
+        /* Still need more space, try a realloc. */
+        old = this->lb_buffer.release();
+        this->lb_share_manager.invalidate_refs();
+        tmp = (char *) realloc(old, new_max);
+        if (tmp != NULL) {
+            this->lb_buffer = tmp;
+            this->lb_buffer_max = new_max;
+        } else {
+            this->lb_buffer = old;
+
+            throw error(ENOMEM);
+        }
     }
 }
 
@@ -249,6 +250,12 @@ throw (error)
 
     require(max_length <= MAX_LINE_BUFFER_SIZE);
 
+    if (this->lb_file_size != -1) {
+        if (start + max_length > this->lb_file_size) {
+            max_length = (this->lb_file_size - start);
+        }
+    }
+
     /*
      * Check to see if the start is inside the cached range or immediately
      * after.
diff --git a/src/line_buffer.hh b/src/line_buffer.hh
index 3677ff61..d2d6997f 100644
--- a/src/line_buffer.hh
+++ b/src/line_buffer.hh
@@ -230,6 +230,7 @@ private:
         char *retval;
 
         require(buffer_offset >= 0);
+        require(this->lb_buffer_size >= buffer_offset);
 
         retval    = &this->lb_buffer[buffer_offset];
         avail_out = this->lb_buffer_size - buffer_offset;