diff --git a/Makefile b/Makefile
index a0cb5c5264..03b6846e4d 100644
--- a/Makefile
+++ b/Makefile
@@ -57,9 +57,6 @@ OBJDIR  := $(MAINOBJDIR)/$(ARCH)/$(ONEVERSION)
 OBJEXTSDIR := $(OBJDIR)/$(EXTSDIR)
 OBJEXTSINCL := $(foreach dir,$(EXTSPACKAGES),-I'$(OBJEXTSDIR)/$(dir)')
 TSTDIR     := $(MAINTSTDIR)/$(ARCH)/$(ONEVERSION)
-ifeq ($(OFFLOAD_CC),)
-EXE_NAMES := $(basename $(notdir $(filter-out %.cu, $(ALL_EXE_FILES))))
-endif
 ifneq ($(LD_SHARED),)
 	ARCHIVE_EXT := .so
 else
@@ -87,31 +84,24 @@ endif
 # File type is derived from name. Only the following extensions are supported:
 #   .F    ->  Fortran
 #   .c    ->  C
-#   .cu   ->  CUDA
-#   .cc   ->  HIP
 #   .h    ->  C header
-#   .hpp  ->  CUDA or HIP header
+#   .cu   ->  CUDA or HIP kernel
 
 ALL_SRC_DIRS := $(shell find $(SRCDIR) -type d | awk '{printf("%s:",$$1)}')
 ALL_PKG_FILES  = $(shell find $(SRCDIR) -name "PACKAGE")
 OBJ_SRC_FILES  = $(shell cd $(SRCDIR); find . -name "*.F")
 OBJ_SRC_FILES += $(shell cd $(SRCDIR); find . -name "*.c")
 
-ifneq (,$(findstring nvcc,$(OFFLOAD_CC)))
+ifneq ($(OFFLOAD_CC),)
 OBJ_SRC_FILES += $(shell cd $(SRCDIR); find . -name "*.cu")
 endif
 
-ifneq (,$(findstring hipcc,$(OFFLOAD_CC)))
-OBJ_SRC_FILES += $(shell cd $(SRCDIR); find . -name "*.cc")
-endif
-
 # Included files used by Fypp preprocessor
 INCLUDED_SRC_FILES = $(notdir $(shell find $(SRCDIR) -name "*.fypp"))
 
 # Include also source files which won't compile into an object file
 ALL_SRC_FILES  = $(strip $(subst $(NULL) .,$(NULL) $(SRCDIR),$(NULL) $(OBJ_SRC_FILES)))
 ALL_SRC_FILES += $(shell find $(SRCDIR) -name "*.h")
-ALL_SRC_FILES += $(shell find $(SRCDIR) -name "*.hpp")
 
 ALL_OBJECTS        = $(addsuffix .o, $(basename $(notdir $(OBJ_SRC_FILES))))
 ALL_EXE_OBJECTS    = $(addsuffix .o, $(EXE_NAMES))
@@ -489,9 +479,6 @@ vpath %.h     $(ALL_SRC_DIRS)
 vpath %.f90   $(ALL_SRC_DIRS)
 vpath %.cu    $(ALL_SRC_DIRS)
 vpath %.c     $(ALL_SRC_DIRS)
-vpath %.cpp   $(ALL_SRC_DIRS)
-vpath %.cxx   $(ALL_SRC_DIRS)
-vpath %.cc    $(ALL_SRC_DIRS)
 
 #
 # Add additional dependency of cp2k_info.F to git-HEAD.
@@ -531,8 +518,15 @@ FYPPFLAGS ?= -n
 %.o: %.cu
 	$(OFFLOAD_CC) -c $(OFFLOAD_FLAGS) $<
 
+# Disable built-in rules for C++.
 %.o: %.cc
-	$(OFFLOAD_CC) -c $(OFFLOAD_FLAGS) $<
+	@echo "Error: C++ is not supported: $<"; false
+
+%.o: %.cpp
+	@echo "Error: C++ is not supported: $<"; false
+
+%.o: %.C
+	@echo "Error: C++ is not supported: $<"; false
 
 ifneq ($(LIBDIR),)
 $(LIBDIR)/%:
diff --git a/src/dbm/dbm_multiply_gpu.cc b/src/dbm/dbm_multiply_gpu.cc
deleted file mode 120000
index 2452325c05..0000000000
--- a/src/dbm/dbm_multiply_gpu.cc
+++ /dev/null
@@ -1 +0,0 @@
-dbm_multiply_gpu.cu
\ No newline at end of file
diff --git a/src/grid/hip/grid_hip_collocate.cc b/src/grid/hip/grid_hip_collocate.cu
similarity index 100%
rename from src/grid/hip/grid_hip_collocate.cc
rename to src/grid/hip/grid_hip_collocate.cu
diff --git a/src/grid/hip/grid_hip_context.cc b/src/grid/hip/grid_hip_context.cu
similarity index 99%
rename from src/grid/hip/grid_hip_context.cc
rename to src/grid/hip/grid_hip_context.cu
index 78c4d5e8e2..c713bfce7d 100644
--- a/src/grid/hip/grid_hip_context.cc
+++ b/src/grid/hip/grid_hip_context.cu
@@ -26,7 +26,7 @@ extern "C" {
 #include "../common/grid_library.h"
 }
 
-#include "grid_hip_context.hpp"
+#include "grid_hip_context.h"
 #include "grid_hip_internal_header.h"
 
 #include "grid_hip_task_list.h"
diff --git a/src/grid/hip/grid_hip_context.hpp b/src/grid/hip/grid_hip_context.h
similarity index 99%
rename from src/grid/hip/grid_hip_context.hpp
rename to src/grid/hip/grid_hip_context.h
index 0f2aa772e4..ad7f5bf4b8 100644
--- a/src/grid/hip/grid_hip_context.hpp
+++ b/src/grid/hip/grid_hip_context.h
@@ -11,8 +11,8 @@
    - Advanced Micro Devices, Inc.
 */
 
-#ifndef GRID_HIP_CONTEXT_HPP
-#define GRID_HIP_CONTEXT_HPP
+#ifndef GRID_HIP_CONTEXT_H
+#define GRID_HIP_CONTEXT_H
 
 #include <hip/hip_runtime_api.h>
 #include <vector>
diff --git a/src/grid/hip/grid_hip_integrate.cc b/src/grid/hip/grid_hip_integrate.cu
similarity index 99%
rename from src/grid/hip/grid_hip_integrate.cc
rename to src/grid/hip/grid_hip_integrate.cu
index 1323bdf529..a1d5438aec 100644
--- a/src/grid/hip/grid_hip_integrate.cc
+++ b/src/grid/hip/grid_hip_integrate.cu
@@ -23,7 +23,7 @@
 #include <stdlib.h>
 #include <string.h>
 
-#include "grid_hip_context.hpp"
+#include "grid_hip_context.h"
 #include "grid_hip_internal_header.h"
 #include "grid_hip_process_vab.h"
 
diff --git a/src/grid/hip/grid_hip_internal_header.h b/src/grid/hip/grid_hip_internal_header.h
index 078a37c438..3800bdcdda 100644
--- a/src/grid/hip/grid_hip_internal_header.h
+++ b/src/grid/hip/grid_hip_internal_header.h
@@ -29,7 +29,7 @@ extern "C" {
 #include "../common/grid_constants.h"
 }
 
-#include "grid_hip_context.hpp"
+#include "grid_hip_context.h"
 
 namespace rocm_backend {
 
diff --git a/src/pw/gpu/pw_gpu_kernels_hip.cc b/src/pw/gpu/pw_gpu_kernels_hip.cc
deleted file mode 120000
index 6b0c313e2f..0000000000
--- a/src/pw/gpu/pw_gpu_kernels_hip.cc
+++ /dev/null
@@ -1 +0,0 @@
-pw_gpu_kernels_cuda.cu
\ No newline at end of file
diff --git a/tools/precommit/precommit.py b/tools/precommit/precommit.py
index 2728ab7899..5aa5bbb843 100755
--- a/tools/precommit/precommit.py
+++ b/tools/precommit/precommit.py
@@ -187,11 +187,11 @@ def process_file(fn, allow_modifications):
         run_local_tool("./tools/doxify/doxify.sh", fn)
         run_prettify(fn)
 
-    if re.match(r".*\.(c|cu|cc|h|hpp)$", fn):
+    if re.match(r".*\.(c|cu|h)$", fn):
         run_remote_tool("clangformat", fn)
 
-    if re.match(r".*\.(cpp|cxx|hcc|hxx)$", fn):
-        raise Exception(f"File extension not supported by build system.")
+    if re.match(r".*\.(cc|cpp|cxx|hcc|hpp|hxx)$", fn):
+        raise Exception(f"C++ is not supported.")
 
     if re.match(r"(.*/PACKAGE)|(.*\.py)$", fn):
         ast.parse(orig_content, filename=fn)