diff --git a/uisimulator/common/Makefile b/uisimulator/common/Makefile
index e2b6b2a4f8..62a124ac97 100644
--- a/uisimulator/common/Makefile
+++ b/uisimulator/common/Makefile
@@ -25,8 +25,9 @@ DEBUG = -g
 # Use this for simulator-only files
 INCLUDES = -I. -I$(OBJDIR) -I$(FIRMDIR)/export -I$(APPSDIR) -I$(ROOTDIR)/uisimulator/$(SIMVER)
 
-SRC := $(shell cat SOURCES | gcc -DMEMORYSIZE=$(MEMORYSIZE) $(INCLUDES) \
- $(TARGET) $(DEFINES) $(EXTRA_DEFINES) -E -P -include "config.h" - )
+# This sets up 'SRC' based on the files mentioned in SOURCES
+include $(TOOLSDIR)/makesrc.inc
+
 OBJS := $(SRC:%.c=$(OBJDIR)/%.o)
 
 DEFINES := -DHAVE_CONFIG_H -DGETTIMEOFDAY_TWO_ARGS -DSIMULATOR \
diff --git a/uisimulator/win32/Makefile b/uisimulator/win32/Makefile
index f429cad8b5..f04a54bdd4 100644
--- a/uisimulator/win32/Makefile
+++ b/uisimulator/win32/Makefile
@@ -29,8 +29,9 @@ INCLUDES = -I. -I$(SIMCOMMON) -I$(OBJDIR) -I$(FIRMDIR)/export -I$(APPSDIR)
 DEFINES = -DHAVE_CONFIG_H -DGETTIMEOFDAY_TWO_ARGS -DSIMULATOR \
 $(TARGET) -DAPPSVERSION=\"$(VERSION)\" -DMEM=${MEMORYSIZE} $(EXTRA_DEFINES)
 
-SRC := $(shell cat SOURCES | gcc -DMEMORYSIZE=$(MEMORYSIZE) $(INCLUDES) \
- $(TARGET) $(DEFINES) $(EXTRA_DEFINES) -E -P -include "config.h" - )
+# This sets up 'SRC' based on the files mentioned in SOURCES
+include $(TOOLSDIR)/makesrc.inc
+
 OBJS := $(SRC:%.c=$(OBJDIR)/%.o)
 
 SOURCES = $(SRC)
diff --git a/uisimulator/x11/Makefile b/uisimulator/x11/Makefile
index 0c0c31183d..f032c664be 100644
--- a/uisimulator/x11/Makefile
+++ b/uisimulator/x11/Makefile
@@ -27,8 +27,9 @@ DEBUG = -g
 # Use this for simulator-only files
 INCLUDES = -I. -I$(SIMCOMMON) -I$(OBJDIR) -I$(FIRMDIR)/export -I$(APPSDIR)
 
-SRC := $(shell cat SOURCES | $(CC) -DMEMORYSIZE=$(MEMORYSIZE) $(INCLUDES) \
- $(TARGET) $(DEFINES) $(EXTRA_DEFINES) -E -P -include "config.h" - )
+# This sets up 'SRC' based on the files mentioned in SOURCES
+include $(TOOLSDIR)/makesrc.inc
+
 OBJS := $(SRC:%.c=$(OBJDIR)/%.o)
 
 DEFINES := -DHAVE_CONFIG_H -DGETTIMEOFDAY_TWO_ARGS -DSIMULATOR \