diff --git a/gnu/packages/maths.scm b/gnu/packages/maths.scm
index 86643b3ae3..e57eaa0536 100644
--- a/gnu/packages/maths.scm
+++ b/gnu/packages/maths.scm
@@ -2247,7 +2247,7 @@ (define-public lpsolve
 (define-public dealii
   (package
     (name "dealii")
-    (version "8.2.1")
+    (version "8.4.1")
     (source
      (origin
        (method url-fetch)
@@ -2255,8 +2255,7 @@ (define-public dealii
                            "download/v" version "/dealii-" version ".tar.gz"))
        (sha256
         (base32
-         "185jych0gdnpkjwxni7pd0dda149492zwq2457xdjg76bzj78mnp"))
-       (patches (search-patches "dealii-p4est-interface.patch"))
+         "1bdksvvyp1rj37df1ndh8j3x9nzpc3sazw8nd0hzvnlw0qnyk800"))
        (modules '((guix build utils)))
        (snippet
         ;; Remove bundled sources: UMFPACK, TBB, muParser, and boost
diff --git a/gnu/packages/patches/dealii-p4est-interface.patch b/gnu/packages/patches/dealii-p4est-interface.patch
deleted file mode 100644
index 4c4125d16c..0000000000
--- a/gnu/packages/patches/dealii-p4est-interface.patch
+++ /dev/null
@@ -1,62 +0,0 @@
-From upstream commit f764598c.
-
-The p4est_connectivity_load function used to take an unsigned long as argument,
-but this has been changed to size_t in p4est 1.0. This makes no difference on
-64 bit systems, but leads to compiler errors on 32 bit systems. Fix this.
-
---- a/source/distributed/tria.cc
-+++ b/source/distributed/tria.cc
-@@ -204,7 +204,11 @@ namespace internal
-       static
-       int (&connectivity_is_valid) (types<2>::connectivity *connectivity);
- 
--#if DEAL_II_P4EST_VERSION_GTE(0,3,4,3)
-+#if DEAL_II_P4EST_VERSION_GTE(1,0,0,0)
-+      static
-+      types<2>::connectivity *(&connectivity_load) (const char *filename,
-+                                                    size_t *length);
-+#elif DEAL_II_P4EST_VERSION_GTE(0,3,4,3)
-       static
-       types<2>::connectivity *(&connectivity_load) (const char *filename,
-                                                     long unsigned *length);
-@@ -384,7 +388,12 @@ namespace internal
-                                                 *connectivity)
-       = p4est_connectivity_is_valid;
- 
--#if DEAL_II_P4EST_VERSION_GTE(0,3,4,3)
-+#if DEAL_II_P4EST_VERSION_GTE(1,0,0,0)
-+    types<2>::connectivity *
-+    (&functions<2>::connectivity_load) (const char *filename,
-+                                        size_t *length)
-+      = p4est_connectivity_load;
-+#elif DEAL_II_P4EST_VERSION_GTE(0,3,4,3)
-     types<2>::connectivity *
-     (&functions<2>::connectivity_load) (const char *filename,
-                                         long unsigned *length)
-@@ -564,7 +573,11 @@ namespace internal
-       static
-       int (&connectivity_is_valid) (types<3>::connectivity *connectivity);
- 
--#if DEAL_II_P4EST_VERSION_GTE(0,3,4,3)
-+#if DEAL_II_P4EST_VERSION_GTE(1,0,0,0)
-+      static
-+      types<3>::connectivity *(&connectivity_load) (const char *filename,
-+                                                    size_t *length);
-+#elif DEAL_II_P4EST_VERSION_GTE(0,3,4,3)
-       static
-       types<3>::connectivity *(&connectivity_load) (const char *filename,
-                                                     long unsigned *length);
-@@ -747,7 +760,12 @@ namespace internal
-                                                 *connectivity)
-       = p8est_connectivity_is_valid;
- 
--#if DEAL_II_P4EST_VERSION_GTE(0,3,4,3)
-+#if DEAL_II_P4EST_VERSION_GTE(1,0,0,0)
-+    types<3>::connectivity *
-+    (&functions<3>::connectivity_load) (const char *filename,
-+                                        size_t *length)
-+      = p8est_connectivity_load;
-+#elif DEAL_II_P4EST_VERSION_GTE(0,3,4,3)
-     types<3>::connectivity *
-     (&functions<3>::connectivity_load) (const char *filename,
-                                         long unsigned *length)