diff --git a/external/pdfium/Library_pdfium.mk b/external/pdfium/Library_pdfium.mk
index a5f6b908c176..62f83e022f6d 100644
--- a/external/pdfium/Library_pdfium.mk
+++ b/external/pdfium/Library_pdfium.mk
@@ -30,6 +30,7 @@ $(eval $(call gb_Library_set_include,pdfium,\
     -I$(gb_UnpackedTarball_workdir)/pdfium/third_party \
     -I$(gb_UnpackedTarball_workdir)/pdfium/third_party/agg23 \
     $(if $(filter TRUE,$(SYSTEM_ABSEIL)),$(ABSEIL_CFLAGS),-I$(gb_UnpackedTarball_workdir)/pdfium/third_party/abseil-cpp) \
+    $(if $(filter TRUE,$(SYSTEM_FAST_FLOAT)),$(FAST_FLOAT_CFLAGS),-I$(gb_UnpackedTarball_workdir)/pdfium/third_party/fast_float) \
     $(if $(filter TRUE,$(SYSTEM_OPENJPEG2)),$(OPENJPEG2_CFLAGS)) \
     $$(INCLUDE) \
 ))
@@ -55,6 +56,11 @@ $(eval $(call gb_Library_add_defs,pdfium,\
     -DUSE_SYSTEM_ABSEIL \
 ))
 endif
+ifeq ($(SYSTEM_FAST_FLOAT),TRUE)
+$(eval $(call gb_Library_add_defs,pdfium,\
+    -DUSE_SYSTEM_FAST_FLOAT \
+))
+endif
 
 
 $(eval $(call gb_Library_set_generated_cxx_suffix,pdfium,cpp))
diff --git a/external/pdfium/UnpackedTarball_pdfium.mk b/external/pdfium/UnpackedTarball_pdfium.mk
index b07ab25633a1..ace1b59ba6a5 100644
--- a/external/pdfium/UnpackedTarball_pdfium.mk
+++ b/external/pdfium/UnpackedTarball_pdfium.mk
@@ -18,6 +18,8 @@ pdfium_patches += freebsd.patch
 
 pdfium_patches += system-abseil.diff
 
+pdfium_patches += system-fast_float.diff
+
 # https://pdfium-review.googlesource.com/c/pdfium/+/130970
 pdfium_patches += retrieve-MIME-type-from-PDF-attachments.patch.1
 
--- /dev/null	2025-09-07 13:37:44.795180713 +0200
+++ external/pdfium/system-fast_float.diff	2025-09-21 11:57:05.388796757 +0200
@@ -0,0 +1,30 @@
+diff -urN pdfium/core/fxcrt/fx_extension.cpp pdfium.new/core/fxcrt/fx_extension.cpp
+--- core/fxcrt/fx_extension.cpp	2025-02-10 19:49:22.000000000 +0100
++++ core/fxcrt/fx_extension.cpp	2025-09-21 11:53:43.310869830 +0200
+@@ -16,7 +16,11 @@
+ #include "core/fxcrt/fx_system.h"
+ #include "core/fxcrt/utf16.h"
+ #include "core/fxcrt/widestring.h"
++#ifdef USE_SYSTEM_FAST_FLOAT
++#include <fast_float/fast_float.h>
++#else
+ #include "third_party/fast_float/src/include/fast_float/fast_float.h"
++#endif
+ 
+ namespace {
+ 
+diff -urN pdfium/core/fxcrt/fx_string.cpp pdfium.new/core/fxcrt/fx_string.cpp
+--- core/fxcrt/fx_string.cpp	2025-02-10 19:49:22.000000000 +0100
++++ core/fxcrt/fx_string.cpp	2025-09-21 11:53:03.382500482 +0200
+@@ -20,7 +20,11 @@
+ #include "core/fxcrt/span.h"
+ #include "core/fxcrt/utf16.h"
+ #include "core/fxcrt/widestring.h"
++#ifdef USE_SYSTEM_FAST_FLOAT
++#include <fast_float/fast_float.h>
++#else
+ #include "third_party/fast_float/src/include/fast_float/fast_float.h"
++#endif
+ 
+ #if !defined(WCHAR_T_IS_16_BIT) && !defined(WCHAR_T_IS_32_BIT)
+ #error "Unknown wchar_t size"