diff --git a/src/util-parser.scm b/src/util-parser.scm
index 84d9d1c..72bcf09 100644
--- a/src/util-parser.scm
+++ b/src/util-parser.scm
@@ -41,11 +41,28 @@
  ;; Pass 0: Removes any comments and removes any leading and trailing
  ;; whitespace.
  (define (parser-preprocess-line line)
-   (irregex-replace (irregex "[ \\t]*$" 'u)
-		    (irregex-replace (irregex "^[ \\t]*" 'u)
-				     (irregex-replace (irregex "#.*$" 'u) line "")
-				     "")
-		    ""))
+   (let* ((llen (string-length line))
+	  (ppos (let ploop ((pidx 0))
+		  (if (or (= pidx llen)
+			  (not (let ((ch (string-ref line pidx)))
+				 (or (eq? ch #\space)
+				     (eq? ch #\tab)))))
+		      pidx
+		      (ploop (add1 pidx)))))
+	  (hpos (let hloop ((hidx ppos))
+		  (if (or (= hidx llen)
+			  (eq? (string-ref line hidx) #\#))
+		      hidx
+		      (hloop (add1 hidx)))))
+	  (spos (let sloop ((sidx (sub1 hpos)))
+		  (if (< sidx ppos)
+		      ppos
+		      (let ((ch (string-ref line sidx)))
+			(if (or (eq? ch #\space)
+				(eq? ch #\tab))
+			    (sloop (sub1 sidx))
+			    (add1 sidx)))))))
+     (substring line ppos spos)))
 
  ;; Pass 1: Expects line with comments and surrounding whitespace
  ;; removed, returns either #f if nothing was parsed, symbol if only