diff --git a/guix-data-service/web/compare/html.scm b/guix-data-service/web/compare/html.scm
index 44acb81..6979e42 100644
--- a/guix-data-service/web/compare/html.scm
+++ b/guix-data-service/web/compare/html.scm
@@ -930,7 +930,7 @@ enough builds to determine a change")))
                                              ,target))
                                    (td ,@(if base-derivation-file-name
                                              `((a (@ (style "display: block;")
-                                                     (href ,base-derivation-file-name))
+                                                     (href ,(uri-encode-filename base-derivation-file-name)))
                                                   (span (@ (class "text-danger glyphicon glyphicon-minus pull-left")
                                                            (style "font-size: 1.5em; padding-right: 0.4em;")))
                                                   ,@(build-statuses->build-status-labels
@@ -939,7 +939,7 @@ enough builds to determine a change")))
                                              '())
                                        ,@(if target-derivation-file-name
                                              `((a (@ (style "display: block; clear: left;")
-                                                     (href ,target-derivation-file-name))
+                                                     (href ,(uri-encode-filename target-derivation-file-name)))
                                                   (span (@ (class "text-success glyphicon glyphicon-plus pull-left")
                                                            (style "font-size: 1.5em; padding-right: 0.4em;")))
                                                   ,@(build-statuses->build-status-labels
@@ -955,9 +955,9 @@ enough builds to determine a change")))
                                                       ,(string-append
                                                         "/compare/derivation?"
                                                         "base_derivation="
-                                                        base-derivation-file-name
+                                                        (uri-encode-filename base-derivation-file-name)
                                                         "&target_derivation="
-                                                        target-derivation-file-name)))
+                                                        (uri-encode-filename target-derivation-file-name))))
                                                   "⇕ Compare"))
                                              '()))))))
                             system-and-versions)))