diff --git a/includes/kore.h b/includes/kore.h
index 97689c0..77a4206 100644
--- a/includes/kore.h
+++ b/includes/kore.h
@@ -358,8 +358,7 @@ u_int8_t	*kore_buf_release(struct kore_buf *, u_int32_t *);
 void	kore_buf_appendf(struct kore_buf *, const char *, ...);
 void	kore_buf_appendv(struct kore_buf *, struct buf_vec *, u_int16_t);
 void	kore_buf_appendb(struct kore_buf *, struct kore_buf *);
-void	kore_buf_replace_string(struct kore_buf *, const char *,
-	    void *, size_t);
+void	kore_buf_replace_string(struct kore_buf *, char *, void *, size_t);
 
 struct spdy_header_block	*spdy_header_block_create(int);
 struct spdy_stream	*spdy_stream_lookup(struct connection *, u_int32_t);
diff --git a/src/buf.c b/src/buf.c
index 827b042..f30d3f1 100644
--- a/src/buf.c
+++ b/src/buf.c
@@ -98,8 +98,7 @@ kore_buf_free(struct kore_buf *buf)
 }
 
 void
-kore_buf_replace_string(struct kore_buf *b, const char *src,
-    void *dst, size_t len)
+kore_buf_replace_string(struct kore_buf *b, char *src, void *dst, size_t len)
 {
 	u_int32_t	blen, off, off2;
 	size_t		nlen, klen;
@@ -112,7 +111,8 @@ kore_buf_replace_string(struct kore_buf *b, const char *src,
 		nlen = blen + len;
 		p = (char *)b->data;
 
-		if ((key = strstr((p + off), src)) == NULL)
+		key = kore_mem_find(p + off, b->offset - off, src, klen);
+		if (key == NULL)
 			break;
 
 		end = key + klen;