It was applied, then reverted (by mistake?) in 4d2c55348bc014.

It's been resubmitted here:
https://lists.gnu.org/archive/html/jami/2024-01/msg00005.html

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 8d71b84b..36729698 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -136,7 +136,7 @@ set(CMAKE_MODULE_PATH
   ${CMAKE_MODULE_PATH} "${EXTRAS_DIR}/build/cmake/modules")
 find_package(LibJami REQUIRED)
 if(LIBJAMI_FOUND)
-  include_directories(${LIBJAMI_INCLUDE_DIRS})
+  include_directories(${LIBJAMI_INCLUDE_DIR})
 endif()
 
 include(FindPython3)
diff --git a/extras/build/cmake/modules/FindLibJami.cmake b/extras/build/cmake/modules/FindLibJami.cmake
index 5cce45fc..11746cd8 100644
--- a/extras/build/cmake/modules/FindLibJami.cmake
+++ b/extras/build/cmake/modules/FindLibJami.cmake
@@ -20,30 +20,19 @@
 
 # Once done, this find module will set:
 #
-#   LIBJAMI_INCLUDE_DIRS - libjami include directories
+#   LIBJAMI_INCLUDE_DIR - libjami include directory
 #   LIBJAMI_FOUND - whether it was able to find the include directories
 #   LIBJAMI_LIB - path to libjami or libring library
 
 set(LIBJAMI_FOUND true)
 
 if(WITH_DAEMON_SUBMODULE)
-  set(LIBJAMI_INCLUDE_DIRS ${DAEMON_DIR}/src/jami)
+  set(LIBJAMI_INCLUDE_DIR ${DAEMON_DIR}/src/jami)
 else()
-  if(EXISTS ${LIBJAMI_INCLUDE_DIR}/jami.h)
-    set(LIBJAMI_INCLUDE_DIRS ${LIBJAMI_INCLUDE_DIR})
-  elseif(EXISTS ${LIBJAMI_BUILD_DIR}/jami/jami.h)
-    set(LIBJAMI_INCLUDE_DIRS ${LIBJAMI_BUILD_DIR}/jami)
-  elseif(EXISTS ${RING_INCLUDE_DIR}/jami.h)
-    set(LIBJAMI_INCLUDE_DIRS ${RING_INCLUDE_DIR})
-  elseif(EXISTS ${RING_BUILD_DIR}/jami/jami.h)
-    set(LIBJAMI_INCLUDE_DIRS ${RING_BUILD_DIR}/jami)
-  elseif(EXISTS ${CMAKE_INSTALL_PREFIX}/include/jami/jami.h)
-    set(LIBJAMI_INCLUDE_DIRS ${CMAKE_INSTALL_PREFIX}/include/jami)
-  elseif(EXISTS ${CMAKE_INSTALL_PREFIX}/daemon/include/jami/jami.h)
-    set(LIBJAMI_INCLUDE_DIRS ${CMAKE_INSTALL_PREFIX}/daemon/include/jami)
-  else()
+  find_path(LIBJAMI_INCLUDE_DIR jami.h PATH_SUFFIXES jami)
+  if(NOT LIBJAMI_INCLUDE_DIR)
     message(STATUS "Jami daemon headers not found!
-Set -DLIBJAMI_BUILD_DIR or -DCMAKE_INSTALL_PREFIX")
+To build using the daemon git submodule, set -DWITH_DAEMON_SUBMODULE")
     set(LIBJAMI_FOUND false)
   endif()
 endif()
@@ -115,5 +104,5 @@ endif()
 # Restore the original value of CMAKE_FIND_LIBRARY_SUFFIXES.
 set(CMAKE_FIND_LIBRARY_SUFFIXES ${CMAKE_FIND_LIBRARY_SUFFIXES_orig})
 
-message(STATUS "Jami daemon headers are in " ${LIBJAMI_INCLUDE_DIRS})
+message(STATUS "Jami daemon headers are in " ${LIBJAMI_INCLUDE_DIR})
 message(STATUS "Jami daemon library is at " ${LIBJAMI_LIB})
diff --git a/src/libclient/CMakeLists.txt b/src/libclient/CMakeLists.txt
index 144efaf5..cb87fc2a 100644
--- a/src/libclient/CMakeLists.txt
+++ b/src/libclient/CMakeLists.txt
@@ -62,7 +62,7 @@ set(CMAKE_MODULE_PATH
   ${CMAKE_MODULE_PATH} "${EXTRAS_DIR}/build/cmake/modules")
 find_package(LibJami REQUIRED)
 if(LIBJAMI_FOUND)
-  include_directories(${LIBJAMI_INCLUDE_DIRS})
+  include_directories(${LIBJAMI_INCLUDE_DIR})
 endif()
 
 string(SUBSTRING ${CMAKE_GENERATOR} 0 14 CMAKE_GENERATOR_SHORT)
diff --git a/src/libclient/qtwrapper/CMakeLists.txt b/src/libclient/qtwrapper/CMakeLists.txt
index 46887051..a20658ad 100644
--- a/src/libclient/qtwrapper/CMakeLists.txt
+++ b/src/libclient/qtwrapper/CMakeLists.txt
@@ -46,7 +46,7 @@ else()
 endif()
 
 include_directories(${CMAKE_CURRENT_SOURCE_DIR})
-include_directories(${LIBJAMI_INCLUDE_DIRS})
+include_directories(${LIBJAMI_INCLUDE_DIR})
 include_directories(${CMAKE_CURRENT_SOURCE_DIR}/../)
 include_directories(${CMAKE_CURRENT_SOURCE_DIR}/../dbus)
 
r><td><span title='2020-04-15 19:26:55 +0200'>2020-04-15</span></td><td><a href='/guix/commit/Makefile.am?id=bd21acf6c390e4fe87eb6053f0b5185d6ecbcf9f'>Merge branch 'master' into core-updates</a></td><td>Marius Bakke</td></tr>
<tr><td><span title='2020-04-10 12:26:21 +0200'>2020-04-10</span></td><td><a href='/guix/commit/Makefile.am?id=08b14ab20ebe181690df6210a0b3f95bad494af5'>maint: 'release' targets runs ./bootstrap for new version string.</a><span class='msg-avail'>...</span></td><td>Ludovic Courtès</td></tr>
<tr><td><span title='2020-04-09 16:32:38 +0200'>2020-04-09</span></td><td><a href='/guix/commit/Makefile.am?id=98148830c0afb9adc8acf150afc48f09aae42ac1'>maint: 'release' builds with '--fallback'.</a><span class='msg-avail'>...</span></td><td>Ludovic Courtès</td></tr>
<tr><td><span title='2020-04-09 13:18:13 +0200'>2020-04-09</span></td><td><a href='/guix/commit/Makefile.am?id=8b292ffd3cd969286ee9cbdb70fde8cf384b9b8b'>maint: 'release' target no longer uses -K, to allow for offloading.</a><span class='msg-avail'>...</span></td><td>Ludovic Courtès</td></tr>
<tr><td><span title='2020-04-09 11:52:23 +0200'>2020-04-09</span></td><td><a href='/guix/commit/Makefile.am?id=808084e9d1ba7d78621bf4c441c7ddb616849683'>maint: Binary tarball uses "guile3.0-guix", not "guix".</a><span class='msg-avail'>...</span></td><td>Ludovic Courtès</td></tr>
<tr><td><span title='2020-03-27 00:12:15 +0100'>2020-03-27</span></td><td><a href='/guix/commit/Makefile.am?id=18af6870370226b4d502d7372844e7f2aded5887'>Merge branch 'master' into core-updates</a><span class='msg-avail'>...</span></td><td>Marius Bakke</td></tr>
<tr><td><span title='2020-03-22 20:55:37 -0700'>2020-03-22</span></td><td><a href='/guix/commit/Makefile.am?id=37f8c50cdc2e99189c74999319f3a1854d419546'>gnu: linux-libre-arm-veyron: Deprecate package.</a><span class='msg-avail'>...</span></td><td>Vagrant Cascadian</td></tr>
<tr><td><span title='2020-03-14 13:13:40 +0100'>2020-03-14</span></td><td><a href='/guix/commit/Makefile.am?id=961d2ee2695b38503b463d055e9c7edbcc0bf307'>Merge branch 'master' into core-updates</a></td><td>Marius Bakke</td></tr>
<tr><td><span title='2020-03-13 17:33:38 +0100'>2020-03-13</span></td><td><a href='/guix/commit/Makefile.am?id=f292c5019111f92b6850afdca4b59f4146b9be3b'>maint: Add 'etc/release-manifest.scm'.</a><span class='msg-avail'>...</span></td><td>Ludovic Courtès</td></tr>
<tr><td><span title='2020-03-10 20:50:02 +0100'>2020-03-10</span></td><td><a href='/guix/commit/Makefile.am?id=50b99c90c87642f664f9c9523a6e40fc8542ddcf'>Merge branch 'master' into core-updates</a></td><td>Marius Bakke</td></tr>