diff --git a/gnu/packages/gnuzilla.scm b/gnu/packages/gnuzilla.scm
index 0ef0c7f673..b5d5013066 100644
--- a/gnu/packages/gnuzilla.scm
+++ b/gnu/packages/gnuzilla.scm
@@ -694,8 +694,8 @@ (define* (computed-origin-method gexp-promise hash-algo hash
                       #:system system
                       #:guile-for-build guile)))
 
-(define %icecat-version "78.6.1-guix0-preview1")
-(define %icecat-build-id "20210107000000") ;must be of the form YYYYMMDDhhmmss
+(define %icecat-version "78.7.0-guix0-preview1")
+(define %icecat-build-id "20210126000000") ;must be of the form YYYYMMDDhhmmss
 
 ;; 'icecat-source' is a "computed" origin that generates an IceCat tarball
 ;; from the corresponding upstream Firefox ESR tarball, using the 'makeicecat'
@@ -717,11 +717,11 @@ (define icecat-source
                   "firefox-" upstream-firefox-version ".source.tar.xz"))
             (sha256
              (base32
-              "1kp75838a38x4h0w98qn01g9asn7jlgm64bz7n70353bnr6bf1qd"))))
+              "0hqnc98k4irq0lsp154binrl0c6kxy6xmab3ss9jwx6d53dl380s"))))
 
-         (upstream-icecat-base-version "78.6.1") ; maybe older than base-version
+         (upstream-icecat-base-version "78.7.0") ; maybe older than base-version
          ;;(gnuzilla-commit (string-append "v" upstream-icecat-base-version))
-         (gnuzilla-commit "10ca84bd9d255caeed506ef36bd3dbe2ad6375ab")
+         (gnuzilla-commit "abfe5eebaca3c2787f1a9505669393674493c177")
          (gnuzilla-source
           (origin
             (method git-fetch)
@@ -733,7 +733,7 @@ (define icecat-source
                                       (string-take gnuzilla-commit 8)))
             (sha256
              (base32
-              "07i3pfbzprnmzrilsh13jjrrk0jixpb9nrrqxzzdvzr2gz06vw29"))))
+              "00ws3540x5whpicc5fx4k949ff73cqvajz6jp13ahn49wqdads47"))))
 
          ;; 'search-patch' returns either a valid file name or #f, so wrap it
          ;; in 'assume-valid-file-name' to avoid 'local-file' warnings.
diff --git a/gnu/packages/patches/icecat-makeicecat.patch b/gnu/packages/patches/icecat-makeicecat.patch
index 3f16880260..edd1ced257 100644
--- a/gnu/packages/patches/icecat-makeicecat.patch
+++ b/gnu/packages/patches/icecat-makeicecat.patch
@@ -25,7 +25,7 @@ index 8be2362..48716f2 100755
 -wget -N https://ftp.mozilla.org/pub/mozilla.org/firefox/releases/${FFVERSION}esr/source/firefox-${FFVERSION}esr.source.tar.xz.asc
 -gpg --recv-keys --keyserver keyserver.ubuntu.com 14F26682D0916CDD81E37B6D61B7B526D98F0353
 -gpg --verify firefox-${FFVERSION}esr.source.tar.xz.asc
--echo -n 0d07b74cb66b94018e3d7f11531f95c76a955e0016a3c401241d0d85062ae7ce firefox-${FFVERSION}esr.source.tar.xz |sha256sum -c -
+-echo -n 1aa041db28cd742e93d663a9da8defd33040b38d8b9470350538473251621643 firefox-${FFVERSION}esr.source.tar.xz |sha256sum -c -
 -
 -echo Extracting Firefox tarball
 -tar -xf firefox-${FFVERSION}esr.source.tar.xz
@@ -37,7 +37,7 @@ index 8be2362..48716f2 100755
 +# wget -N https://ftp.mozilla.org/pub/mozilla.org/firefox/releases/${FFVERSION}esr/source/firefox-${FFVERSION}esr.source.tar.xz.asc
 +# gpg --recv-keys --keyserver keyserver.ubuntu.com 14F26682D0916CDD81E37B6D61B7B526D98F0353
 +# gpg --verify firefox-${FFVERSION}esr.source.tar.xz.asc
-+# echo -n 0d07b74cb66b94018e3d7f11531f95c76a955e0016a3c401241d0d85062ae7ce firefox-${FFVERSION}esr.source.tar.xz |sha256sum -c -
++# echo -n 1aa041db28cd742e93d663a9da8defd33040b38d8b9470350538473251621643 firefox-${FFVERSION}esr.source.tar.xz |sha256sum -c -
 +# 
 +# echo Extracting Firefox tarball
 +# tar -xf firefox-${FFVERSION}esr.source.tar.xz