diff --git a/src/CMakeLists.txt b/src/CMakeLists.txt
index 8c90fab424..60d9067669 100644
--- a/src/CMakeLists.txt
+++ b/src/CMakeLists.txt
@@ -1169,6 +1169,7 @@ set (PCH_SOURCES
 	events.cpp
 	GuillotineBinPack.cpp
 	SkylineBinPack.cpp
+	tmpfileplus.cpp
 )
 
 enable_precompiled_headers( g_pch.h PCH_SOURCES )
@@ -1183,7 +1184,6 @@ add_executable( zdoom WIN32 MACOSX_BUNDLE
 	${PCH_SOURCES}
 	x86.cpp
 	strnatcmp.c
-	tmpfileplus.c
 	zstring.cpp
 	math/asin.c
 	math/atan.c
diff --git a/src/tmpfileplus.c b/src/tmpfileplus.cpp
similarity index 99%
rename from src/tmpfileplus.c
rename to src/tmpfileplus.cpp
index ddb71de092..5475d8f8fd 100644
--- a/src/tmpfileplus.c
+++ b/src/tmpfileplus.cpp
@@ -217,7 +217,7 @@ static FILE *mktempfile_internal(const char *tmpdir, const char *pfx, char **tmp
 
 	lentempname = strlen(tmpdir) + strlen(FILE_SEPARATOR) + strlen(pfx) + strlen(randpart);
 	DPRINTF1("lentempname=%d\n", lentempname);
-	tmpname = malloc(lentempname + 1);
+	tmpname = (char*)malloc(lentempname + 1);
 	if (!tmpname)
 	{
 		errno = ENOMEM;