diff --git a/Tuprules.tup b/Tuprules.tup
index 8430a0047..59b39de69 100644
--- a/Tuprules.tup
+++ b/Tuprules.tup
@@ -5,12 +5,14 @@ OUTPUTS_DEV=$(TUP_CWD)/dev
 DEV_DIR = $(TUP_CWD)/dev
 
 ifeq (@(TUP_ARCH),i386)
+X86 = y
 CC_MARCH = -march=i686 -m32
 LD_MARCH = -melf_i386
 AS_MARCH = -march=i686 --32
 endif
 
 ifeq (@(TUP_ARCH),x86_64)
+X86 = y
 TOOL_CHAIN_PREFIX=genode-x86-
 CC_MARCH = -m64 -mcmodel=large
 LD_MARCH = -melf_x86_64
@@ -92,7 +94,12 @@ PKG_CONFIG_DIR = $(OUTPUTS_DEV)/lib/pkgconfig
 PKG_CONFIG = PKG_CONFIG_PATH=$(PKG_CONFIG_DIR):$PKG_CONFIG_PATH pkg-config
 
 DEFINES += -g
+
+ifdef OLEVEL
+OLEVEL = @(OLEVEL)
+else
 OLEVEL = -O0
+endif
 
 !ir = | $(GENODE_DIR)/<pkg-config> |> clang $(OLEVEL) $(DEFINES) $(CXXFLAGS) $(CXXFLAGS_%e) $(CXXFLAGS_%f) `$(PKG_CONFIG) --cflags $(LIBS)` $(INCLUDES) -S -emit-llvm %f |> %B.ll
 
diff --git a/repos/base-nova/src/core/Tupfile b/repos/base-nova/src/core/Tupfile
index d82351964..b4c356b88 100644
--- a/repos/base-nova/src/core/Tupfile
+++ b/repos/base-nova/src/core/Tupfile
@@ -1,5 +1,3 @@
-ifeq (@(BUILD_NOVA),y)
-
 include_rules
 GEN_CORE_DIR = $(BASE_DIR)/src/core
 
@@ -55,5 +53,3 @@ CXXFLAGS_$(GEN_CORE_DIR)/version.cc += -DGENODE_VERSION=\"`git describe`\"
 	|> $(LD) $(LD_MARCH) -u _start --whole-archive -r \
 		%<base-common> %<base-libs> %f -o %o \
 	|> core-nova.o $(REP_DIR)/<core>
-
-endif
diff --git a/repos/base-nova/src/lib/base/Tupfile b/repos/base-nova/src/lib/base/Tupfile
index ce9511afb..ffa7c67b3 100644
--- a/repos/base-nova/src/lib/base/Tupfile
+++ b/repos/base-nova/src/lib/base/Tupfile
@@ -1,5 +1,3 @@
-ifeq (@(BUILD_NOVA),y)
-
 include_rules
 INCLUDES += -I$(BASE_DIR)/src/include
 
@@ -42,5 +40,3 @@ SRC_CC += \
 : foreach $(SRC_CC) |> !cxx |> {base-obj}
 
 : {base-obj} |> !ar |> base-nova.lib.a
-
-endif
diff --git a/repos/base-nova/src/lib/ld/Tupfile b/repos/base-nova/src/lib/ld/Tupfile
index 5ccc377f4..f77dee361 100644
--- a/repos/base-nova/src/lib/ld/Tupfile
+++ b/repos/base-nova/src/lib/ld/Tupfile
@@ -1,5 +1,3 @@
-ifeq (@(BUILD_NOVA),y)
-
 TARGET_NAME = base-nova
 include_rules
 INCLUDES += -I$(BASE_DIR)/src/include
@@ -59,5 +57,3 @@ LDFLAGS += `pkg-config --static --libs $(BASE_PKGS)`
 
 : {bin} |> !collect_bin |>
 include &(BIN_RULES)
-
-endif
diff --git a/repos/os/src/drivers/ahci/spec/x86/Tupfile b/repos/os/src/drivers/ahci/spec/x86/Tupfile
index ec96bd7cc..481a281c5 100644
--- a/repos/os/src/drivers/ahci/spec/x86/Tupfile
+++ b/repos/os/src/drivers/ahci/spec/x86/Tupfile
@@ -1,7 +1,7 @@
-ifdef x86
-
 TARGET_NAME = ahci_drv
 include_rules
+ifneq ($(X86),)
+
 : foreach $(SRC_CC) *.cc |> !cxx |> %B.o {obj}
 : {obj} |  |> !prg |> $(TARGET_NAME) {bin}
 : {bin} |> !collect_bin |>
diff --git a/repos/os/src/drivers/input/spec/ps2/x86/Tupfile b/repos/os/src/drivers/input/spec/ps2/x86/Tupfile
index 2ccac1b7e..63a606342 100644
--- a/repos/os/src/drivers/input/spec/ps2/x86/Tupfile
+++ b/repos/os/src/drivers/input/spec/ps2/x86/Tupfile
@@ -1,7 +1,7 @@
-ifdef x86
-
 TARGET_NAME = ps2_drv
 include_rules
+ifneq ($(X86),)
+
 : foreach $(SRC_CC) *.cc |> !cxx |> %B.o {obj}
 : {obj} |  |> !prg |> $(TARGET_NAME) {bin}
 : {bin} |> !collect_bin |>