diff --git a/app/config/Makefile.am b/app/config/Makefile.am
index be87b441fc..f6f3d0017a 100644
--- a/app/config/Makefile.am
+++ b/app/config/Makefile.am
@@ -132,10 +132,10 @@ CLEANFILES = $(EXTRA_PROGRAMS) foorc
 # rules to generate built sources
 #
 # setup autogeneration dependencies
-gen_sources = xgen-dec
+gen_sources = xgen-cec
 CLEANFILES += $(gen_sources)
 
-$(srcdir)/config-enums.c: $(srcdir)/config-enums.h $(GIMP_MKENUMS)
+xgen-cec: $(srcdir)/config-enums.h $(GIMP_MKENUMS) Makefile.am
 	$(AM_V_GEN) (cd $(srcdir) && $(GIMP_MKENUMS) \
 		--fhead "#include \"config.h\"\n#include <gio/gio.h>\n#include \"libgimpbase/gimpbase.h\"\n#include \"config-enums.h\"\n#include\"gimp-intl.h\"" \
 		--fprod "\n/* enumerations from \"@filename@\" */" \
@@ -145,7 +145,15 @@ $(srcdir)/config-enums.c: $(srcdir)/config-enums.h $(GIMP_MKENUMS)
 		--dhead "  static const Gimp@Type@Desc descs[] =\n  {" \
 		--dprod "    { @VALUENAME@, @valuedesc@, @valuehelp@ }," \
 		--dtail "    { 0, NULL, NULL }\n  };\n\n  static GType type = 0;\n\n  if (G_UNLIKELY (! type))\n    {\n      type = g_@type@_register_static (\"@EnumName@\", values);\n      gimp_type_set_translation_context (type, \"@enumnick@\");\n      gimp_@type@_set_value_descriptions (type, descs);\n    }\n\n  return type;\n}\n" \
-		config-enums.h) > xgen-dec \
-	&& cp xgen-dec $@ \
-	&& rm -f xgen-dec
+		config-enums.h) > $@
 
+$(srcdir)/config-enums.c: xgen-cec
+	$(AM_V_GEN) if ! cmp -s $< $@; then \
+		cp $< $@; \
+	else \
+		# if the file hasn't changed, only update its timestamp, so that \
+		# the receipe doesn't get executed again next time, but allow this \
+		# to fail (e.g., when using a read-only source directory). \
+		touch $@ 2> /dev/null \
+		|| true; \
+	fi
diff --git a/app/core/Makefile.am b/app/core/Makefile.am
index 9e99352349..63e734d869 100644
--- a/app/core/Makefile.am
+++ b/app/core/Makefile.am
@@ -450,7 +450,7 @@ gimpmarshal.c: gimpmarshal.h
 	&& cp xgen-gmc $(@F) \
 	&& rm -f xgen-gmc xgen-gmc~
 
-$(srcdir)/core-enums.c: $(srcdir)/core-enums.h $(GIMP_MKENUMS)
+xgen-cec: $(srcdir)/core-enums.h $(GIMP_MKENUMS) Makefile.am
 	$(AM_V_GEN) (cd $(srcdir) && $(GIMP_MKENUMS) \
 		--fhead "#include \"config.h\"\n#include <gio/gio.h>\n#include \"libgimpbase/gimpbase.h\"\n#include \"core-enums.h\"\n#include \"gimp-intl.h\"" \
 		--fprod "\n/* enumerations from \"@filename@\" */" \
@@ -460,6 +460,15 @@ $(srcdir)/core-enums.c: $(srcdir)/core-enums.h $(GIMP_MKENUMS)
 		--dhead "  static const Gimp@Type@Desc descs[] =\n  {" \
 		--dprod "    { @VALUENAME@, @valuedesc@, @valuehelp@ }," \
 		--dtail "    { 0, NULL, NULL }\n  };\n\n  static GType type = 0;\n\n  if (G_UNLIKELY (! type))\n    {\n      type = g_@type@_register_static (\"@EnumName@\", values);\n      gimp_type_set_translation_context (type, \"@enumnick@\");\n      gimp_@type@_set_value_descriptions (type, descs);\n    }\n\n  return type;\n}\n" \
-		core-enums.h) > xgen-cec \
-	&& cp xgen-cec $@ \
-	&& rm -f xgen-cec
+		core-enums.h) > $@
+
+$(srcdir)/core-enums.c: xgen-cec
+	$(AM_V_GEN) if ! cmp -s $< $@; then \
+		cp $< $@; \
+	else \
+		# if the file hasn't changed, only update its timestamp, so that \
+		# the receipe doesn't get executed again next time, but allow this \
+		# to fail (e.g., when using a read-only source directory). \
+		touch $@ 2> /dev/null \
+		|| true; \
+	fi
diff --git a/app/display/Makefile.am b/app/display/Makefile.am
index a7cd6ac1d9..46acb10428 100644
--- a/app/display/Makefile.am
+++ b/app/display/Makefile.am
@@ -178,7 +178,7 @@ libappdisplay_a_SOURCES = \
 gen_sources = xgen-dec
 CLEANFILES = $(gen_sources)
 
-$(srcdir)/display-enums.c: $(srcdir)/display-enums.h $(GIMP_MKENUMS)
+xgen-dec: $(srcdir)/display-enums.h $(GIMP_MKENUMS) Makefile.am
 	$(AM_V_GEN) (cd $(srcdir) && $(GIMP_MKENUMS) \
 		--fhead "#include \"config.h\"\n#include <gio/gio.h>\n#include \"libgimpbase/gimpbase.h\"\n#include \"display-enums.h\"\n#include\"gimp-intl.h\"" \
 		--fprod "\n/* enumerations from \"@filename@\" */" \
@@ -188,6 +188,15 @@ $(srcdir)/display-enums.c: $(srcdir)/display-enums.h $(GIMP_MKENUMS)
 		--dhead "  static const Gimp@Type@Desc descs[] =\n  {" \
 		--dprod "    { @VALUENAME@, @valuedesc@, @valuehelp@ }," \
 		--dtail "    { 0, NULL, NULL }\n  };\n\n  static GType type = 0;\n\n  if (G_UNLIKELY (! type))\n    {\n      type = g_@type@_register_static (\"@EnumName@\", values);\n      gimp_type_set_translation_context (type, \"@enumnick@\");\n      gimp_@type@_set_value_descriptions (type, descs);\n    }\n\n  return type;\n}\n" \
-		display-enums.h) > xgen-dec \
-	&& cp xgen-dec $@ \
-	&& rm -f xgen-dec
+		display-enums.h) > $@
+
+$(srcdir)/display-enums.c: xgen-dec
+	$(AM_V_GEN) if ! cmp -s $< $@; then \
+		cp $< $@; \
+	else \
+		# if the file hasn't changed, only update its timestamp, so that \
+		# the receipe doesn't get executed again next time, but allow this \
+		# to fail (e.g., when using a read-only source directory). \
+		touch $@ 2> /dev/null \
+		|| true; \
+	fi
diff --git a/app/gegl/Makefile.am b/app/gegl/Makefile.am
index 5cfdc154d9..a6a7f4f9c0 100644
--- a/app/gegl/Makefile.am
+++ b/app/gegl/Makefile.am
@@ -49,10 +49,10 @@ libappgegl_a_SOURCES = $(libappgegl_a_built_sources) $(libappgegl_a_sources)
 # rules to generate built sources
 #
 # setup autogeneration dependencies
-gen_sources = xgen-tec
+gen_sources = xgen-ggec
 CLEANFILES = $(gen_sources)
 
-$(srcdir)/gimp-gegl-enums.c: $(srcdir)/gimp-gegl-enums.h $(GIMP_MKENUMS)
+xgen-ggec: $(srcdir)/gimp-gegl-enums.h $(GIMP_MKENUMS) Makefile.am
 	$(AM_V_GEN) (cd $(srcdir) && $(GIMP_MKENUMS) \
 		--fhead "#include \"config.h\"\n#include <gio/gio.h>\n#include \"libgimpbase/gimpbase.h\"\n#include \"core/core-enums.h\"\n#include \"gimp-gegl-enums.h\"\n#include \"gimp-intl.h\"" \
 		--fprod "\n/* enumerations from \"@filename@\" */" \
@@ -62,6 +62,15 @@ $(srcdir)/gimp-gegl-enums.c: $(srcdir)/gimp-gegl-enums.h $(GIMP_MKENUMS)
 		--dhead "  static const Gimp@Type@Desc descs[] =\n  {" \
 		--dprod "    { @VALUENAME@, @valuedesc@, @valuehelp@ }," \
 		--dtail "    { 0, NULL, NULL }\n  };\n\n  static GType type = 0;\n\n  if (G_UNLIKELY (! type))\n    {\n      type = g_@type@_register_static (\"@EnumName@\", values);\n      gimp_type_set_translation_context (type, \"@enumnick@\");\n      gimp_@type@_set_value_descriptions (type, descs);\n    }\n\n  return type;\n}\n" \
-		gimp-gegl-enums.h) > xgen-tec \
-	&& cp xgen-tec $@ \
-	&& rm -f xgen-tec
+		gimp-gegl-enums.h) > $@
+
+$(srcdir)/gimp-gegl-enums.c: xgen-ggec
+	$(AM_V_GEN) if ! cmp -s $< $@; then \
+		cp $< $@; \
+	else \
+		# if the file hasn't changed, only update its timestamp, so that \
+		# the receipe doesn't get executed again next time, but allow this \
+		# to fail (e.g., when using a read-only source directory). \
+		touch $@ 2> /dev/null \
+		|| true; \
+	fi
diff --git a/app/operations/Makefile.am b/app/operations/Makefile.am
index a342f9ae9a..2abca9eb95 100644
--- a/app/operations/Makefile.am
+++ b/app/operations/Makefile.am
@@ -108,10 +108,10 @@ libappoperations_a_SOURCES = \
 # rules to generate built sources
 #
 # setup autogeneration dependencies
-gen_sources = xgen-pec
+gen_sources = xgen-oec
 CLEANFILES = $(gen_sources)
 
-$(srcdir)/operations-enums.c: $(srcdir)/operations-enums.h $(GIMP_MKENUMS)
+xgen-oec: $(srcdir)/operations-enums.h $(GIMP_MKENUMS) Makefile.am
 	$(AM_V_GEN) (cd $(srcdir) && $(GIMP_MKENUMS) \
 		--fhead "#include \"config.h\"\n#include <gio/gio.h>\n#include \"libgimpbase/gimpbase.h\"\n#include \"operations-enums.h\"\n#include \"gimp-intl.h\"" \
 		--fprod "\n/* enumerations from \"@filename@\" */" \
@@ -121,6 +121,15 @@ $(srcdir)/operations-enums.c: $(srcdir)/operations-enums.h $(GIMP_MKENUMS)
 		--dhead "  static const Gimp@Type@Desc descs[] =\n  {" \
 		--dprod "    { @VALUENAME@, @valuedesc@, @valuehelp@ }," \
 		--dtail "    { 0, NULL, NULL }\n  };\n\n  static GType type = 0;\n\n  if (G_UNLIKELY (! type))\n    {\n      type = g_@type@_register_static (\"@EnumName@\", values);\n      gimp_type_set_translation_context (type, \"@enumnick@\");\n      gimp_@type@_set_value_descriptions (type, descs);\n    }\n\n  return type;\n}\n" \
-		operations-enums.h) > xgen-pec \
-	&& cp xgen-pec $@ \
-	&& rm -f xgen-pec
+		operations-enums.h) > $@
+
+$(srcdir)/operations-enums.c: xgen-oec
+	$(AM_V_GEN) if ! cmp -s $< $@; then \
+		cp $< $@; \
+	else \
+		# if the file hasn't changed, only update its timestamp, so that \
+		# the receipe doesn't get executed again next time, but allow this \
+		# to fail (e.g., when using a read-only source directory). \
+		touch $@ 2> /dev/null \
+		|| true; \
+	fi
diff --git a/app/paint/Makefile.am b/app/paint/Makefile.am
index 4a14926274..66df99f8f9 100644
--- a/app/paint/Makefile.am
+++ b/app/paint/Makefile.am
@@ -98,7 +98,7 @@ libapppaint_a_SOURCES = $(libapppaint_a_built_sources) $(libapppaint_a_sources)
 gen_sources = xgen-pec
 CLEANFILES = $(gen_sources)
 
-$(srcdir)/paint-enums.c: $(srcdir)/paint-enums.h $(GIMP_MKENUMS)
+xgen-pec: $(srcdir)/paint-enums.h $(GIMP_MKENUMS) Makefile.am
 	$(AM_V_GEN) (cd $(srcdir) && $(GIMP_MKENUMS) \
 		--fhead "#include \"config.h\"\n#include <gio/gio.h>\n#include \"libgimpbase/gimpbase.h\"\n#include \"paint-enums.h\"\n#include \"gimp-intl.h\"" \
 		--fprod "\n/* enumerations from \"@filename@\" */" \
@@ -108,6 +108,15 @@ $(srcdir)/paint-enums.c: $(srcdir)/paint-enums.h $(GIMP_MKENUMS)
 		--dhead "  static const Gimp@Type@Desc descs[] =\n  {" \
 		--dprod "    { @VALUENAME@, @valuedesc@, @valuehelp@ }," \
 		--dtail "    { 0, NULL, NULL }\n  };\n\n  static GType type = 0;\n\n  if (G_UNLIKELY (! type))\n    {\n      type = g_@type@_register_static (\"@EnumName@\", values);\n      gimp_type_set_translation_context (type, \"@enumnick@\");\n      gimp_@type@_set_value_descriptions (type, descs);\n    }\n\n  return type;\n}\n" \
-		paint-enums.h) > xgen-pec \
-	&& cp xgen-pec $@ \
-	&& rm -f xgen-pec
+		paint-enums.h) > $@
+
+$(srcdir)/paint-enums.c: xgen-pec
+	$(AM_V_GEN) if ! cmp -s $< $@; then \
+		cp $< $@; \
+	else \
+		# if the file hasn't changed, only update its timestamp, so that \
+		# the receipe doesn't get executed again next time, but allow this \
+		# to fail (e.g., when using a read-only source directory). \
+		touch $@ 2> /dev/null \
+		|| true; \
+	fi
diff --git a/app/plug-in/Makefile.am b/app/plug-in/Makefile.am
index 5dbc0ad225..471bf9a559 100644
--- a/app/plug-in/Makefile.am
+++ b/app/plug-in/Makefile.am
@@ -78,10 +78,10 @@ libappplug_in_a_SOURCES = \
 # rules to generate built sources
 #
 # setup autogeneration dependencies
-gen_sources = xgen-bec
+gen_sources = xgen-pec
 CLEANFILES = $(EXTRA_PROGRAMS) $(gen_sources)
 
-$(srcdir)/plug-in-enums.c: $(srcdir)/plug-in-enums.h $(GIMP_MKENUMS)
+xgen-pec: $(srcdir)/plug-in-enums.h $(GIMP_MKENUMS) Makefile.am
 	$(AM_V_GEN) (cd $(srcdir) && $(GIMP_MKENUMS) \
 		--fhead "#include \"config.h\"\n#include <gio/gio.h>\n#include \"libgimpbase/gimpbase.h\"\n#include \"plug-in-enums.h\"\n#include \"gimp-intl.h\"" \
 		--fprod "\n/* enumerations from \"@filename@\" */" \
@@ -91,6 +91,15 @@ $(srcdir)/plug-in-enums.c: $(srcdir)/plug-in-enums.h $(GIMP_MKENUMS)
 		--dhead "  static const Gimp@Type@Desc descs[] =\n  {" \
 		--dprod "    { @VALUENAME@, @valuedesc@, @valuehelp@ }," \
 		--dtail "    { 0, NULL, NULL }\n  };\n\n  static GType type = 0;\n\n  if (G_UNLIKELY (! type))\n    {\n      type = g_@type@_register_static (\"@EnumName@\", values);\n      gimp_type_set_translation_context (type, \"@enumnick@\");\n      gimp_@type@_set_value_descriptions (type, descs);\n    }\n\n  return type;\n}\n" \
-		plug-in-enums.h) > xgen-bec \
-	&& cp xgen-bec $@ \
-	&& rm -f xgen-bec
+		plug-in-enums.h) > $@
+
+$(srcdir)/plug-in-enums.c: xgen-pec
+	$(AM_V_GEN) if ! cmp -s $< $@; then \
+		cp $< $@; \
+	else \
+		# if the file hasn't changed, only update its timestamp, so that \
+		# the receipe doesn't get executed again next time, but allow this \
+		# to fail (e.g., when using a read-only source directory). \
+		touch $@ 2> /dev/null \
+		|| true; \
+	fi
diff --git a/app/text/Makefile.am b/app/text/Makefile.am
index e9bead5813..44966e1ce5 100644
--- a/app/text/Makefile.am
+++ b/app/text/Makefile.am
@@ -57,7 +57,7 @@ libapptext_a_SOURCES = $(libapptext_a_built_sources) $(libapptext_a_sources)
 gen_sources = xgen-tec
 CLEANFILES = $(gen_sources)
 
-$(srcdir)/text-enums.c: $(srcdir)/text-enums.h $(GIMP_MKENUMS)
+xgen-tec: $(srcdir)/text-enums.h $(GIMP_MKENUMS) Makefile.am
 	$(AM_V_GEN) (cd $(srcdir) && $(GIMP_MKENUMS) \
 		--fhead "#include \"config.h\"\n#include <gio/gio.h>\n#include \"libgimpbase/gimpbase.h\"\n#include \"text-enums.h\"\n#include \"gimp-intl.h\"" \
 		--fprod "\n/* enumerations from \"@filename@\" */" \
@@ -67,6 +67,15 @@ $(srcdir)/text-enums.c: $(srcdir)/text-enums.h $(GIMP_MKENUMS)
 		--dhead "  static const Gimp@Type@Desc descs[] =\n  {" \
 		--dprod "    { @VALUENAME@, @valuedesc@, @valuehelp@ }," \
 		--dtail "    { 0, NULL, NULL }\n  };\n\n  static GType type = 0;\n\n  if (G_UNLIKELY (! type))\n    {\n      type = g_@type@_register_static (\"@EnumName@\", values);\n      gimp_type_set_translation_context (type, \"@enumnick@\");\n      gimp_@type@_set_value_descriptions (type, descs);\n    }\n\n  return type;\n}\n" \
-		text-enums.h) > xgen-tec \
-	&& cp xgen-tec $@ \
-	&& rm -f xgen-tec
+		text-enums.h) > $@
+
+$(srcdir)/text-enums.c: xgen-tec
+	$(AM_V_GEN) if ! cmp -s $< $@; then \
+		cp $< $@; \
+	else \
+		# if the file hasn't changed, only update its timestamp, so that \
+		# the receipe doesn't get executed again next time, but allow this \
+		# to fail (e.g., when using a read-only source directory). \
+		touch $@ 2> /dev/null \
+		|| true; \
+	fi
diff --git a/app/tools/Makefile.am b/app/tools/Makefile.am
index 3c6cca4904..73adcc3eaf 100644
--- a/app/tools/Makefile.am
+++ b/app/tools/Makefile.am
@@ -234,7 +234,7 @@ libapptools_a_SOURCES = $(libapptools_a_built_sources) $(libapptools_a_sources)
 gen_sources = xgen-tec
 CLEANFILES = $(gen_sources)
 
-$(srcdir)/tools-enums.c: $(srcdir)/tools-enums.h $(GIMP_MKENUMS)
+xgen-tec: $(srcdir)/tools-enums.h $(GIMP_MKENUMS) Makefile.am
 	$(AM_V_GEN) (cd $(srcdir) && $(GIMP_MKENUMS) \
 		--fhead "#include \"config.h\"\n#include <gio/gio.h>\n#include \"libgimpbase/gimpbase.h\"\n#include \"core/core-enums.h\"\n#include \"tools-enums.h\"\n#include \"gimp-intl.h\"" \
 		--fprod "\n/* enumerations from \"@filename@\" */" \
@@ -244,6 +244,15 @@ $(srcdir)/tools-enums.c: $(srcdir)/tools-enums.h $(GIMP_MKENUMS)
 		--dhead "  static const Gimp@Type@Desc descs[] =\n  {" \
 		--dprod "    { @VALUENAME@, @valuedesc@, @valuehelp@ }," \
 		--dtail "    { 0, NULL, NULL }\n  };\n\n  static GType type = 0;\n\n  if (G_UNLIKELY (! type))\n    {\n      type = g_@type@_register_static (\"@EnumName@\", values);\n      gimp_type_set_translation_context (type, \"@enumnick@\");\n      gimp_@type@_set_value_descriptions (type, descs);\n    }\n\n  return type;\n}\n" \
-		tools-enums.h) > xgen-tec \
-	&& cp xgen-tec $@ \
-	&& rm -f xgen-tec
+		tools-enums.h) > $@
+
+$(srcdir)/tools-enums.c: xgen-tec
+	$(AM_V_GEN) if ! cmp -s $< $@; then \
+		cp $< $@; \
+	else \
+		# if the file hasn't changed, only update its timestamp, so that \
+		# the receipe doesn't get executed again next time, but allow this \
+		# to fail (e.g., when using a read-only source directory). \
+		touch $@ 2> /dev/null \
+		|| true; \
+	fi
diff --git a/app/widgets/Makefile.am b/app/widgets/Makefile.am
index a74dc9408d..66e09944f6 100644
--- a/app/widgets/Makefile.am
+++ b/app/widgets/Makefile.am
@@ -462,7 +462,7 @@ libappwidgets_a_SOURCES = \
 gen_sources = xgen-wec
 CLEANFILES = $(gen_sources)
 
-$(srcdir)/widgets-enums.c: $(srcdir)/widgets-enums.h $(GIMP_MKENUMS)
+xgen-wec: $(srcdir)/widgets-enums.h $(GIMP_MKENUMS) Makefile.am
 	$(AM_V_GEN) (cd $(srcdir) && $(GIMP_MKENUMS) \
 		--fhead "#include \"config.h\"\n#include <gtk/gtk.h>\n#include \"libgimpbase/gimpbase.h\"\n#include \"widgets-enums.h\"\n#include \"gimp-intl.h\"" \
 		--fprod "\n/* enumerations from \"@filename@\" */" \
@@ -472,6 +472,15 @@ $(srcdir)/widgets-enums.c: $(srcdir)/widgets-enums.h $(GIMP_MKENUMS)
 		--dhead "  static const Gimp@Type@Desc descs[] =\n  {" \
 		--dprod "    { @VALUENAME@, @valuedesc@, @valuehelp@ }," \
 		--dtail "    { 0, NULL, NULL }\n  };\n\n  static GType type = 0;\n\n  if (G_UNLIKELY (! type))\n    {\n      type = g_@type@_register_static (\"@EnumName@\", values);\n      gimp_type_set_translation_context (type, \"@enumnick@\");\n      gimp_@type@_set_value_descriptions (type, descs);\n    }\n\n  return type;\n}\n" \
-		widgets-enums.h) > xgen-wec \
-	&& cp xgen-wec $@ \
-	&& rm -f xgen-wec
+		widgets-enums.h) > $@
+
+$(srcdir)/widgets-enums.c: xgen-wec
+	$(AM_V_GEN) if ! cmp -s $< $@; then \
+		cp $< $@; \
+	else \
+		# if the file hasn't changed, only update its timestamp, so that \
+		# the receipe doesn't get executed again next time, but allow this \
+		# to fail (e.g., when using a read-only source directory). \
+		touch $@ 2> /dev/null \
+		|| true; \
+	fi
diff --git a/libgimp/Makefile.am b/libgimp/Makefile.am
index fc437394a5..5ae5e6ae23 100644
--- a/libgimp/Makefile.am
+++ b/libgimp/Makefile.am
@@ -443,7 +443,7 @@ uninstall-local: uninstall-ms-lib uninstall-libtool-import-lib
 gen_sources = xgen-cec xgen-umh xgen-umc
 CLEANFILES = $(gen_sources)
 
-gimpenums.c: $(srcdir)/gimpenums.h $(srcdir)/gimpenums.c.tail $(GIMP_MKENUMS)
+gimpenums.c: $(srcdir)/gimpenums.h $(srcdir)/gimpenums.c.tail $(GIMP_MKENUMS) Makefile.am
 	$(AM_V_GEN) $(GIMP_MKENUMS) \
 		--fhead "#include \"config.h\"\n#include <gio/gio.h>\n#undef GIMP_DISABLE_DEPRECATED\n#include \"libgimpbase/gimpbase.h\"\n#include \"libgimpconfig/gimpconfigenums.h\"\n#include \"gimpenums.h\"" \
 		--fprod "\n/* enumerations from \"@filename@\" */" \
diff --git a/libgimpbase/Makefile.am b/libgimpbase/Makefile.am
index 45a9a2390c..fff0dd3da1 100644
--- a/libgimpbase/Makefile.am
+++ b/libgimpbase/Makefile.am
@@ -201,7 +201,7 @@ EXTRA_PROGRAMS = test-cpu-accel
 gen_sources = xgen-bec xgen-cec
 CLEANFILES = $(EXTRA_PROGRAMS) $(gen_sources)
 
-$(srcdir)/gimpbaseenums.c: $(srcdir)/gimpbaseenums.h $(GIMP_MKENUMS)
+xgen-bec: $(srcdir)/gimpbaseenums.h $(GIMP_MKENUMS) Makefile.am
 	$(AM_V_GEN) (cd $(srcdir) && $(GIMP_MKENUMS) \
 		--fhead "#include \"config.h\"\n#include <glib-object.h>\n#undef GIMP_DISABLE_DEPRECATED\n#include \"gimpbasetypes.h\"\n#include \"libgimp/libgimp-intl.h\"" \
 		--fprod "\n/* enumerations from \"@filename@\" */" \
@@ -211,11 +211,20 @@ $(srcdir)/gimpbaseenums.c: $(srcdir)/gimpbaseenums.h $(GIMP_MKENUMS)
 		--dhead "  static const Gimp@Type@Desc descs[] =\n  {" \
 		--dprod "    { @VALUENAME@, @valuedesc@, @valuehelp@ }," \
 		--dtail "    { 0, NULL, NULL }\n  };\n\n  static GType type = 0;\n\n  if (G_UNLIKELY (! type))\n    {\n      type = g_@type@_register_static (\"@EnumName@\", values);\n      gimp_type_set_translation_domain (type, GETTEXT_PACKAGE \"-libgimp\");\n      gimp_type_set_translation_context (type, \"@enumnick@\");\n      gimp_@type@_set_value_descriptions (type, descs);\n    }\n\n  return type;\n}\n" \
-		gimpbaseenums.h) > xgen-bec \
-	&& cp xgen-bec $@ \
-	&& rm -f xgen-bec
+		gimpbaseenums.h) > $@
 
-$(srcdir)/gimpcompatenums.c: $(srcdir)/gimpcompatenums.h $(GIMP_MKENUMS)
+$(srcdir)/gimpbaseenums.c: xgen-bec
+	$(AM_V_GEN) if ! cmp -s $< $@; then \
+		cp $< $@; \
+	else \
+		# if the file hasn't changed, only update its timestamp, so that \
+		# the receipe doesn't get executed again next time, but allow this \
+		# to fail (e.g., when using a read-only source directory). \
+		touch $@ 2> /dev/null \
+		|| true; \
+	fi
+
+xgen-cec: $(srcdir)/gimpcompatenums.h $(GIMP_MKENUMS) Makefile.am
 	$(AM_V_GEN) (cd $(srcdir) && $(GIMP_MKENUMS) \
 		--fhead "#include \"config.h\"\n#include <glib-object.h>\n#include \"gimpbasetypes.h\"\n#include \"gimpcompatenums.h\"\n#include \"libgimp/libgimp-intl.h\"" \
 		--fprod "\n/* enumerations from \"@filename@\" */" \
@@ -225,9 +234,17 @@ $(srcdir)/gimpcompatenums.c: $(srcdir)/gimpcompatenums.h $(GIMP_MKENUMS)
 		--dhead "  static const Gimp@Type@Desc descs[] =\n  {" \
 		--dprod "    { @VALUENAME@, @valuedesc@, @valuehelp@ }," \
 		--dtail "    { 0, NULL, NULL }\n  };\n\n  static GType type = 0;\n\n  if (G_UNLIKELY (! type))\n    {\n      type = g_@type@_register_static (\"@EnumName@\", values);\n      gimp_type_set_translation_domain (type, GETTEXT_PACKAGE \"-libgimp\");\n      gimp_type_set_translation_context (type, \"@enumnick@\");\n      gimp_@type@_set_value_descriptions (type, descs);\n    }\n\n  return type;\n}\n" \
-		gimpcompatenums.h) > xgen-cec \
-	&& cp xgen-cec $@ \
-	&& rm -f xgen-cec
+		gimpcompatenums.h) > $@
 
+$(srcdir)/gimpcompatenums.c: xgen-cec
+	$(AM_V_GEN) if ! cmp -s $< $@; then \
+		cp $< $@; \
+	else \
+		# if the file hasn't changed, only update its timestamp, so that \
+		# the receipe doesn't get executed again next time, but allow this \
+		# to fail (e.g., when using a read-only source directory). \
+		touch $@ 2> /dev/null \
+		|| true; \
+	fi
 
 DISTCLEANFILES = gimpversion.h
diff --git a/libgimpconfig/Makefile.am b/libgimpconfig/Makefile.am
index 8664fd9210..1464686124 100644
--- a/libgimpconfig/Makefile.am
+++ b/libgimpconfig/Makefile.am
@@ -138,7 +138,7 @@ uninstall-local: uninstall-ms-lib uninstall-libtool-import-lib
 gen_sources = xgen-cec
 CLEANFILES = $(gen_sources)
 
-$(srcdir)/gimpconfigenums.c: $(srcdir)/gimpconfigenums.h $(GIMP_MKENUMS)
+xgen-cec: $(srcdir)/gimpconfigenums.h $(GIMP_MKENUMS) Makefile.am
 	$(AM_V_GEN) (cd $(srcdir) && $(GIMP_MKENUMS) \
 		--fhead "#include \"config.h\"\n#include <gio/gio.h>\n#include \"libgimpbase/gimpbase.h\"\n#include \"gimpconfigenums.h\"\n#include \"libgimp/libgimp-intl.h\"" \
 		--fprod "\n/* enumerations from \"@filename@\" */" \
@@ -148,6 +148,15 @@ $(srcdir)/gimpconfigenums.c: $(srcdir)/gimpconfigenums.h $(GIMP_MKENUMS)
 		--dhead "  static const Gimp@Type@Desc descs[] =\n  {" \
 		--dprod "    { @VALUENAME@, @valuedesc@, @valuehelp@ }," \
 		--dtail "    { 0, NULL, NULL }\n  };\n\n  static GType type = 0;\n\n  if (G_UNLIKELY (! type))\n    {\n      type = g_@type@_register_static (\"@EnumName@\", values);\n      gimp_type_set_translation_domain (type, GETTEXT_PACKAGE \"-libgimp\");\n      gimp_type_set_translation_context (type, \"@enumnick@\");\n      gimp_@type@_set_value_descriptions (type, descs);\n    }\n\n  return type;\n}\n" \
-		gimpconfigenums.h) > xgen-cec \
-	&& cp xgen-cec $@ \
-	&& rm -f xgen-cec
+		gimpconfigenums.h) > $@
+
+$(srcdir)/gimpconfigenums.c: xgen-cec
+	$(AM_V_GEN) if ! cmp -s $< $@; then \
+		cp $< $@; \
+	else \
+		# if the file hasn't changed, only update its timestamp, so that \
+		# the receipe doesn't get executed again next time, but allow this \
+		# to fail (e.g., when using a read-only source directory). \
+		touch $@ 2> /dev/null \
+		|| true; \
+	fi
diff --git a/libgimpthumb/Makefile.am b/libgimpthumb/Makefile.am
index 5406d0c1b3..267f1aa156 100644
--- a/libgimpthumb/Makefile.am
+++ b/libgimpthumb/Makefile.am
@@ -111,7 +111,7 @@ uninstall-local: uninstall-ms-lib uninstall-libtool-import-lib
 gen_sources = xgen-tec
 CLEANFILES = $(gen_sources)
 
-gimpthumb-enums.c: $(srcdir)/gimpthumb-enums.h $(GIMP_MKENUMS)
+gimpthumb-enums.c: $(srcdir)/gimpthumb-enums.h $(GIMP_MKENUMS) Makefile.am
 	$(AM_V_GEN) $(GIMP_MKENUMS) \
 		--fhead "#include \"config.h\"\n#include <glib-object.h>\n#include \"gimpthumb-enums.h\"" \
 		--fprod "\n/* enumerations from \"@filename@\" */" \
diff --git a/libgimpwidgets/Makefile.am b/libgimpwidgets/Makefile.am
index 7a8bee0397..0ad3e55c4e 100644
--- a/libgimpwidgets/Makefile.am
+++ b/libgimpwidgets/Makefile.am
@@ -307,7 +307,7 @@ endif
 gen_sources = xgen-wec xgen-wmh xgen-wmc
 CLEANFILES = $(gen_sources)
 
-$(srcdir)/gimpwidgetsenums.c: $(srcdir)/gimpwidgetsenums.h $(GIMP_MKENUMS)
+xgen-wec: $(srcdir)/gimpwidgetsenums.h $(GIMP_MKENUMS) Makefile.am
 	$(AM_V_GEN) (cd $(srcdir) && $(GIMP_MKENUMS) \
 		--fhead "#include \"config.h\"\n#include <gio/gio.h>\n#include \"libgimpbase/gimpbase.h\"\n#include \"gimpwidgetsenums.h\"\n#include \"libgimp/libgimp-intl.h\"" \
 		--fprod "\n/* enumerations from \"@filename@\" */" \
@@ -317,9 +317,18 @@ $(srcdir)/gimpwidgetsenums.c: $(srcdir)/gimpwidgetsenums.h $(GIMP_MKENUMS)
 		--dhead "  static const Gimp@Type@Desc descs[] =\n  {" \
 		--dprod "    { @VALUENAME@, @valuedesc@, @valuehelp@ }," \
 		--dtail "    { 0, NULL, NULL }\n  };\n\n  static GType type = 0;\n\n  if (G_UNLIKELY (! type))\n    {\n      type = g_@type@_register_static (\"@EnumName@\", values);\n      gimp_type_set_translation_domain (type, GETTEXT_PACKAGE \"-libgimp\");\n      gimp_type_set_translation_context (type, \"@enumnick@\");\n      gimp_@type@_set_value_descriptions (type, descs);\n    }\n\n  return type;\n}\n" \
-		gimpwidgetsenums.h) > xgen-wec \
-	&& cp xgen-wec $@ \
-	&& rm -f xgen-wec
+		gimpwidgetsenums.h) > $@
+
+$(srcdir)/gimpwidgetsenums.c: xgen-wec
+	$(AM_V_GEN) if ! cmp -s $< $@; then \
+		cp $< $@; \
+	else \
+		# if the file hasn't changed, only update its timestamp, so that \
+		# the receipe doesn't get executed again next time, but allow this \
+		# to fail (e.g., when using a read-only source directory). \
+		touch $@ 2> /dev/null \
+		|| true; \
+	fi
 
 gimpwidgetsmarshal.h: $(srcdir)/gimpwidgetsmarshal.list
 	$(AM_V_GEN) $(GLIB_GENMARSHAL) --prefix=_gimp_widgets_marshal $(srcdir)/gimpwidgetsmarshal.list --header >> xgen-wmh \