diff --git a/doomsday/engine/engine.pro b/doomsday/engine/engine.pro
index 48ec2f2751..f503ab476e 100644
--- a/doomsday/engine/engine.pro
+++ b/doomsday/engine/engine.pro
@@ -439,7 +439,7 @@ deng_nodisplaymode {
 
 # Platform-independent sources.
 SOURCES += \
-    portable/src/abstractfile.c \
+    portable/src/abstractfile.cpp \
     portable/src/abstractresource.c \
     portable/src/animator.c \
     portable/src/audiodriver.c \
diff --git a/doomsday/engine/portable/src/abstractfile.c b/doomsday/engine/portable/src/abstractfile.cpp
similarity index 100%
rename from doomsday/engine/portable/src/abstractfile.c
rename to doomsday/engine/portable/src/abstractfile.cpp