diff --git a/core/config.mk b/core/config.mk
index 676bd64..b34bd2b 100644
--- a/core/config.mk
+++ b/core/config.mk
@@ -144,6 +144,8 @@
 # Here since this file is included by envsetup as well as during build.
 include $(BUILD_SYSTEM)/math.mk
 
+include $(BUILD_SYSTEM)/strings.mk
+
 # Various mappings to avoid hard-coding paths all over the place
 include $(BUILD_SYSTEM)/pathmap.mk
 
diff --git a/core/definitions.mk b/core/definitions.mk
index 743d667..995c95f 100644
--- a/core/definitions.mk
+++ b/core/definitions.mk
@@ -3443,35 +3443,6 @@
 endef
 
 ###########################################################
-## Convert to lower case without requiring a shell, which isn't cacheable.
-##
-## $(1): string
-###########################################################
-to-lower=$(subst A,a,$(subst B,b,$(subst C,c,$(subst D,d,$(subst E,e,$(subst F,f,$(subst G,g,$(subst H,h,$(subst I,i,$(subst J,j,$(subst K,k,$(subst L,l,$(subst M,m,$(subst N,n,$(subst O,o,$(subst P,p,$(subst Q,q,$(subst R,r,$(subst S,s,$(subst T,t,$(subst U,u,$(subst V,v,$(subst W,w,$(subst X,x,$(subst Y,y,$(subst Z,z,$1))))))))))))))))))))))))))
-
-###########################################################
-## Convert to upper case without requiring a shell, which isn't cacheable.
-##
-## $(1): string
-###########################################################
-to-upper=$(subst a,A,$(subst b,B,$(subst c,C,$(subst d,D,$(subst e,E,$(subst f,F,$(subst g,G,$(subst h,H,$(subst i,I,$(subst j,J,$(subst k,K,$(subst l,L,$(subst m,M,$(subst n,N,$(subst o,O,$(subst p,P,$(subst q,Q,$(subst r,R,$(subst s,S,$(subst t,T,$(subst u,U,$(subst v,V,$(subst w,W,$(subst x,X,$(subst y,Y,$(subst z,Z,$1))))))))))))))))))))))))))
-
-# Sanity-check to-lower and to-upper
-lower := abcdefghijklmnopqrstuvwxyz-_
-upper := ABCDEFGHIJKLMNOPQRSTUVWXYZ-_
-
-ifneq ($(lower),$(call to-lower,$(upper)))
-  $(error to-lower sanity check failure)
-endif
-
-ifneq ($(upper),$(call to-upper,$(lower)))
-  $(error to-upper sanity check failure)
-endif
-
-lower :=
-upper :=
-
-###########################################################
 ## Verify module name meets character requirements:
 ##   a-z A-Z 0-9
 ##   _.+-,@~
diff --git a/core/strings.mk b/core/strings.mk
new file mode 100644
index 0000000..98dbb0f
--- /dev/null
+++ b/core/strings.mk
@@ -0,0 +1,44 @@
+#
+# Copyright (C) 2018 The Android Open Source Project
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+#
+
+###########################################################
+## Convert to lower case without requiring a shell, which isn't cacheable.
+##
+## $(1): string
+###########################################################
+to-lower=$(subst A,a,$(subst B,b,$(subst C,c,$(subst D,d,$(subst E,e,$(subst F,f,$(subst G,g,$(subst H,h,$(subst I,i,$(subst J,j,$(subst K,k,$(subst L,l,$(subst M,m,$(subst N,n,$(subst O,o,$(subst P,p,$(subst Q,q,$(subst R,r,$(subst S,s,$(subst T,t,$(subst U,u,$(subst V,v,$(subst W,w,$(subst X,x,$(subst Y,y,$(subst Z,z,$1))))))))))))))))))))))))))
+
+###########################################################
+## Convert to upper case without requiring a shell, which isn't cacheable.
+##
+## $(1): string
+###########################################################
+to-upper=$(subst a,A,$(subst b,B,$(subst c,C,$(subst d,D,$(subst e,E,$(subst f,F,$(subst g,G,$(subst h,H,$(subst i,I,$(subst j,J,$(subst k,K,$(subst l,L,$(subst m,M,$(subst n,N,$(subst o,O,$(subst p,P,$(subst q,Q,$(subst r,R,$(subst s,S,$(subst t,T,$(subst u,U,$(subst v,V,$(subst w,W,$(subst x,X,$(subst y,Y,$(subst z,Z,$1))))))))))))))))))))))))))
+
+# Sanity-check to-lower and to-upper
+lower := abcdefghijklmnopqrstuvwxyz-_
+upper := ABCDEFGHIJKLMNOPQRSTUVWXYZ-_
+
+ifneq ($(lower),$(call to-lower,$(upper)))
+  $(error to-lower sanity check failure)
+endif
+
+ifneq ($(upper),$(call to-upper,$(lower)))
+  $(error to-upper sanity check failure)
+endif
+
+lower :=
+upper :=