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)
 
d8110db2c78ebeb7e045f8bac'>gnu: lightning: Update to 2.2.0.</a><span class='msg-avail'>...<span class='msg-tooltip'>gnu/packages/assembly.scm (lightning): Update to 2.2.0.

Signed-off-by: Efraim Flashner &lt;efraim@flashner.co.il&gt;
</span></span></td><td>Andy Tai</td></tr>
<tr><td><span title='2022-08-15 10:22:38 +0200'>2022-08-15</span></td><td><a href='/guix/commit/gnu/packages/assembly.scm?id=eb38d49b04d946c96dbd4ea6adc6ffd394711a13'>gnu: rgbds: Update to 0.5.2.</a><span class='msg-avail'>...<span class='msg-tooltip'>* gnu/packages/assembly.scm (rgbds): Update to 0.5.2.
[arguments]: Remove a trailing #t.

Signed-off-by: Mathieu Othacehe &lt;othacehe@gnu.org&gt;
</span></span></td><td>Ekaitz Zarraga</td></tr>
<tr><td><span title='2022-05-29 23:56:05 +0200'>2022-05-29</span></td><td><a href='/guix/commit/gnu/packages/assembly.scm?id=3d1b2bc740b880c474ee3b178d078a7222315c74'>gnu: wla-dx: Update to 10.1.</a><span class='msg-avail'>...<span class='msg-tooltip'>* gnu/packages/assembly.scm (wla-dx): Update to 10.1.
[native-inputs]: Use new style.
[arguments]: Add custom 'check phase to run run_tests.sh.

Signed-off-by: Ludovic Courtès &lt;ludo@gnu.org&gt;
</span></span></td><td>Felix Gruber</td></tr>
<tr><td><span title='2022-05-01 02:00:00 +0200'>2022-05-01</span></td><td><a href='/guix/commit/gnu/packages/assembly.scm?id=1b61c75ff738b7df62d9c793e80f866b594e8bb0'>gnu: fasm: Update to 1.73.30.</a><span class='msg-avail'>...<span class='msg-tooltip'>* gnu/packages/assembly.scm (fasm): Update to 1.73.30.
</span></span></td><td>Tobias Geerinckx-Rice</td></tr>