diff --git a/gnu/local.mk b/gnu/local.mk
index 04f895b71f..1578f4f9df 100644
--- a/gnu/local.mk
+++ b/gnu/local.mk
@@ -1320,6 +1320,7 @@ dist_patch_DATA =						\
   %D%/packages/patches/flatpak-fix-fonts-icons.patch	\
   %D%/packages/patches/flatpak-fix-icon-validation.patch	\
   %D%/packages/patches/flatpak-unset-gdk-pixbuf-for-sandbox.patch	\
+  %D%/packages/patches/flex-fix-make-dependencies.patch         \
   %D%/packages/patches/fluxbox-1.3.7-no-dynamic-cursor.patch	\
   %D%/packages/patches/fluxbox-1.3.7-gcc.patch			\
   %D%/packages/patches/fmt-9-overspecified-tests.patch	\
diff --git a/gnu/packages/commencement.scm b/gnu/packages/commencement.scm
index c591ed1c76..d387abb92e 100644
--- a/gnu/packages/commencement.scm
+++ b/gnu/packages/commencement.scm
@@ -2649,6 +2649,7 @@ exec " gcc-bin "/" program
   ;; This Flex is needed to build MiG as well as Linux-Libre headers.
   (package
     (inherit flex)
+    (source (bootstrap-origin (package-source flex)))
     (native-inputs (list bison-boot0))
     (propagated-inputs (list m4-boot0))
     (inputs (%boot0-inputs))
diff --git a/gnu/packages/flex.scm b/gnu/packages/flex.scm
index 871f1645ba..1e08dbd0e5 100644
--- a/gnu/packages/flex.scm
+++ b/gnu/packages/flex.scm
@@ -26,6 +26,7 @@
   #:use-module (guix gexp)
   #:use-module (guix utils)
   #:use-module (gnu packages)
+  #:use-module (gnu packages bootstrap)
   #:use-module (gnu packages m4)
   #:use-module (gnu packages man)
   #:use-module (gnu packages bison)
@@ -43,7 +44,8 @@
                     "flex-" version ".tar.gz"))
               (sha256
                (base32
-                "15g9bv236nzi665p9ggqjlfn4dwck5835vf0bbw2cz7h5c1swyp8"))))
+                "15g9bv236nzi665p9ggqjlfn4dwck5835vf0bbw2cz7h5c1swyp8"))
+              (patches (search-patches "flex-fix-make-dependencies.patch"))))
     (build-system gnu-build-system)
     (arguments
      (if (%current-target-system)
diff --git a/gnu/packages/patches/flex-fix-make-dependencies.patch b/gnu/packages/patches/flex-fix-make-dependencies.patch
new file mode 100644
index 0000000000..dbe9392a26
--- /dev/null
+++ b/gnu/packages/patches/flex-fix-make-dependencies.patch
@@ -0,0 +1,54 @@
+Retrieved from Poky:
+https://git.enea.com/cgit/linux/poky.git/plain/meta/recipes-devtools/flex/flex/0001-build-tests-add-missing-parser-scanner-dependencies.patch?id=bf94ea1cc4e966fa2cf55206389f9c34fbd5419d
+
+From 47e3916842ffefd7def84ae85758fdcceeb77839 Mon Sep 17 00:00:00 2001
+From: Ross Burton <ross.burton@arm.com>
+Date: Thu, 20 Mar 2025 12:16:50 +0000
+Subject: [PATCH] build(tests): add missing parser->scanner dependencies
+
+With sufficient parallelism and `make --shuffle` to reorder builds the
+test suite occasionally fails to build with errors like this:
+
+ tests/bison_yylval_parser.y:36:10: fatal error: bison_yylval_scanner.h: No such file or directory
+    36 | #include "bison_yylval_scanner.h"
+
+Solve this by adding the missing dependencies to the *_parser.o targets
+on the _scanner.h files.
+
+Upstream-Status: Submitted [https://github.com/westes/flex/pull/702]
+Signed-off-by: Ross Burton <ross.burton@arm.com>
+---
+ tests/Makefile.am | 3 +++
+ 1 file changed, 3 insertions(+)
+
+diff --git a/tests/Makefile.am b/tests/Makefile.am
+index 2cb51df..d0c199d 100644
+--- a/tests/Makefile.am
++++ b/tests/Makefile.am
+@@ -343,6 +343,7 @@ FLEX = $(top_builddir)/src/flex
+ 
+ bison_nr_main.$(OBJEXT): bison_nr_parser.h bison_nr_scanner.h
+ bison_nr_scanner.$(OBJEXT): bison_nr_parser.h
++bison_nr_parser.$(OBJEXT): bison_nr_scanner.h
+ 
+ bison_nr_scanner.h: bison_nr_scanner.c
+ 	@if test ! -f $@; then rm -f $<; else :; fi
+@@ -350,6 +351,7 @@ bison_nr_scanner.h: bison_nr_scanner.c
+ 
+ bison_yylloc_main.$(OBJEXT): bison_yylloc_parser.h bison_yylloc_scanner.h
+ bison_yylloc_scanner.$(OBJEXT): bison_yylloc_parser.h
++bison_yylloc_parser.$(OBJEXT): bison_yylloc_scanner.h
+ 
+ bison_yylloc_scanner.h: bison_yylloc_scanner.c
+ 	@if test ! -f $@; then rm -f $<; else :; fi
+@@ -357,6 +359,7 @@ bison_yylloc_scanner.h: bison_yylloc_scanner.c
+ 
+ bison_yylval_main.$(OBJEXT): bison_yylval_parser.h bison_yylval_scanner.h
+ bison_yylval_scanner.$(OBJEXT): bison_yylval_parser.h
++bison_yylval_parser.$(OBJEXT): bison_yylval_scanner.h
+ 
+ bison_yylval_scanner.h: bison_yylval_scanner.c
+ 	@if test ! -f $@; then rm -f $<; else :; fi
+-- 
+2.43.0
+