diff --git a/apps/1sec.C b/apps/1sec.cpp
similarity index 100%
rename from apps/1sec.C
rename to apps/1sec.cpp
diff --git a/apps/Makefile.am b/apps/Makefile.am
index a9475c8fc8..2399594853 100644
--- a/apps/Makefile.am
+++ b/apps/Makefile.am
@@ -8,6 +8,6 @@ bin_PROGRAMS = upper_case concat 1sec
 LDADD = $(top_builddir)/api/libboinc_api.a $(LIBBOINC) $(PTHREAD_LIBS)
 AM_CXXFLAGS = $(MYSQL_CFLAGS)
 
-upper_case_SOURCES       = upper_case.C
-concat_SOURCES           = concat.C
-1sec_SOURCES             = 1sec.C
+upper_case_SOURCES       = upper_case.cpp
+concat_SOURCES           = concat.cpp
+1sec_SOURCES             = 1sec.cpp
diff --git a/apps/concat.C b/apps/concat.cpp
similarity index 100%
rename from apps/concat.C
rename to apps/concat.cpp
diff --git a/apps/error.C b/apps/error.cpp
similarity index 100%
rename from apps/error.C
rename to apps/error.cpp
diff --git a/apps/upper_case.C b/apps/upper_case.cpp
similarity index 100%
rename from apps/upper_case.C
rename to apps/upper_case.cpp