diff --git a/src/CMakeLists.txt b/src/CMakeLists.txt
index 7ffac4ae2..5c43ab7b4 100644
--- a/src/CMakeLists.txt
+++ b/src/CMakeLists.txt
@@ -77,7 +77,7 @@ add_executable(SRB2SDL2 MACOSX_BUNDLE WIN32
 	r_debug_parser.cpp
 	r_debug_printer.cpp
 	r_draw.cpp
-	r_fps.c
+	r_fps.cpp
 	r_main.cpp
 	r_plane.cpp
 	r_segs.cpp
diff --git a/src/r_fps.c b/src/r_fps.cpp
similarity index 98%
rename from src/r_fps.c
rename to src/r_fps.cpp
index 06016e2e3..ebe15dc36 100644
--- a/src/r_fps.c
+++ b/src/r_fps.cpp
@@ -337,12 +337,12 @@ static void AddInterpolator(levelinterpolator_t* interpolator)
 			levelinterpolators_size *= 2;
 		}
 
-		levelinterpolators = Z_Realloc(
+		levelinterpolators = static_cast<levelinterpolator_t**>(Z_Realloc(
 			(void*) levelinterpolators,
 			sizeof(levelinterpolator_t*) * levelinterpolators_size,
 			PU_LEVEL,
 			NULL
-		);
+		));
 	}
 
 	levelinterpolators[levelinterpolators_len] = interpolator;
@@ -409,8 +409,8 @@ void R_CreateInterpolator_Polyobj(thinker_t *thinker, polyobj_t *polyobj)
 	interp->polyobj.polyobj = polyobj;
 	interp->polyobj.vertices_size = polyobj->numVertices;
 
-	interp->polyobj.oldvertices = Z_Calloc(sizeof(fixed_t) * 2 * polyobj->numVertices, PU_LEVEL, NULL);
-	interp->polyobj.bakvertices = Z_Calloc(sizeof(fixed_t) * 2 * polyobj->numVertices, PU_LEVEL, NULL);
+	interp->polyobj.oldvertices = static_cast<fixed_t*>(Z_Calloc(sizeof(fixed_t) * 2 * polyobj->numVertices, PU_LEVEL, NULL));
+	interp->polyobj.bakvertices = static_cast<fixed_t*>(Z_Calloc(sizeof(fixed_t) * 2 * polyobj->numVertices, PU_LEVEL, NULL));
 	for (size_t i = 0; i < polyobj->numVertices; i++)
 	{
 		interp->polyobj.oldvertices[i * 2    ] = interp->polyobj.bakvertices[i * 2    ] = polyobj->vertices[i]->x;
@@ -667,12 +667,12 @@ void R_AddMobjInterpolator(mobj_t *mobj)
 			interpolated_mobjs_capacity *= 2;
 		}
 
-		interpolated_mobjs = Z_Realloc(
+		interpolated_mobjs = static_cast<mobj_t**>(Z_Realloc(
 			interpolated_mobjs,
 			sizeof(mobj_t *) * interpolated_mobjs_capacity,
 			PU_LEVEL,
 			NULL
-		);
+		));
 	}
 
 	interpolated_mobjs[interpolated_mobjs_len] = mobj;