Precompiled header with both C and C++ files

Hello. To illustrate the issue I'm facing, I created the following simple project:

Code:

---

TEMPLATE = app
CONFIG += console
CONFIG -= app_bundle
CONFIG -= qt
 
CONFIG += precompile_header
PRECOMPILED_HEADER = testpch.h
 
QMAKE_CC = $${QMAKE_CXX}
QMAKE_CFLAGS += -TP
QMAKE_CFLAGS += -EHsc
 
SOURCES += \
main.cpp \
extra.c
 
HEADERS += testpch.h

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The problem is that extra.c is not compiled with the precompiled header, even though it is compiled as a C++ file. main.cpp has in its command line

Code:

---

-FItestpch.h -Yutestpch.h -Fpdebug\testproject_pch.pch

---

, which is not present in the command line for extra.c. How can I determine qmake to introduce the precompiled header also in the case of C files?