diff --git a/interpreters/toywasm/Makefile b/interpreters/toywasm/Makefile
index 6cb3c47b2..e1cabb32a 100644
--- a/interpreters/toywasm/Makefile
+++ b/interpreters/toywasm/Makefile
@@ -74,9 +74,9 @@ CSRCS += wasi_fdtable.c
 # TOYWASM_ENABLE_WASI_THREADS
 CSRCS += wasi_threads.c
 
-CFLAGS += ${shell $(INCDIR) "$(CC)" $(APPDIR)/interpreters/toywasm/include}
-CFLAGS += ${shell $(INCDIR) "$(CC)" $(APPDIR)/interpreters/toywasm/toywasm/lib}
-CFLAGS += ${shell $(INCDIR) "$(CC)" $(APPDIR)/interpreters/toywasm/toywasm/libwasi}
+CFLAGS += ${INCDIR_PREFIX}$(APPDIR)/interpreters/toywasm/include
+CFLAGS += ${INCDIR_PREFIX}$(APPDIR)/interpreters/toywasm/toywasm/lib
+CFLAGS += ${INCDIR_PREFIX}$(APPDIR)/interpreters/toywasm/toywasm/libwasi
 
 TOYWASM_VERSION  = 99468253ca11c9b8df444e3e23865b5030f6af69
 TOYWASM_UNPACK   = toywasm
diff --git a/lte/lapi/src/Make.defs b/lte/lapi/src/Make.defs
index 7ea2d4760..daa284365 100644
--- a/lte/lapi/src/Make.defs
+++ b/lte/lapi/src/Make.defs
@@ -35,6 +35,6 @@ CSRCS = lapi_evt.c      \
 
 DEPPATH += --dep-path src
 VPATH += :src
-CFLAGS += ${shell $(INCDIR) "$(CC)" $(APPDIR)/lte/lapi/src}
+CFLAGS += ${INCDIR_PREFIX}$(APPDIR)/lte/lapi/src
 
 endif
diff --git a/sdr/liquid_dsp/Makefile b/sdr/liquid_dsp/Makefile
index 88c3188f3..2da12bee3 100644
--- a/sdr/liquid_dsp/Makefile
+++ b/sdr/liquid_dsp/Makefile
@@ -39,7 +39,7 @@ $(LIQUID_DSP_UNPACK)/.patch: $(LIQUID_DSP_UNPACK)
 	$(Q) touch $(LIQUID_DSP_UNPACK)/.patch
 
 CFLAGS += -std=c99
-CFLAGS += ${shell $(INCDIR) "$(CC)" $(APPDIR)/sdr/liquid_dsp}
+CFLAGS += ${INCDIR_PREFIX}$(APPDIR)/sdr/liquid_dsp
 CFLAGS += -DM_SQRT1_2=0.7071067811865475244008443621048490
 CFLAGS += -DM_SQRT2=1.4142135623730950488016887242096981
 CFLAGS += -DM_PI=3.1415926535897932384626433832795029