diff --git a/configure/CONFIG_BASE b/configure/CONFIG_BASE
index 236f1457a..2d9d77120 100644
--- a/configure/CONFIG_BASE
+++ b/configure/CONFIG_BASE
@@ -52,8 +52,9 @@ BASE_CPPFLAGS += $(OSITHREAD_DEFAULT_STACK_FLAGS_$(OSITHREAD_USE_DEFAULT_STACK))
 
 #---------------------------------------------------------------
 # Where to find the installed build tools
+#   Windows does not like commands with relative paths starting ../
 
-TOOLS = $(EPICS_BASE_HOST_BIN)
+TOOLS = $(abspath $(EPICS_BASE_HOST_BIN))
 
 #---------------------------------------------------------------
 # Epics base build tools and tool flags
diff --git a/src/ca/legacy/gdd/Makefile b/src/ca/legacy/gdd/Makefile
index 78c69321e..b1e8fceaa 100644
--- a/src/ca/legacy/gdd/Makefile
+++ b/src/ca/legacy/gdd/Makefile
@@ -79,9 +79,9 @@ dbMapper$(DEP): $(COMMON_DIR)/gddApps.h
 
 # Rules for generated files
 #
-$(COMMON_DIR)/aitConvertGenerated.cc: $(TOOLS)/aitGen$(HOSTEXE)
+$(COMMON_DIR)/aitConvertGenerated.cc: $(EPICS_BASE_HOST_BIN)/aitGen$(HOSTEXE)
 	$(TOOLS)/aitGen$(HOSTEXE) $@
 
-$(COMMON_DIR)/gddApps.h : $(TOOLS)/genApps$(HOSTEXE)
+$(COMMON_DIR)/gddApps.h : $(EPICS_BASE_HOST_BIN)/genApps$(HOSTEXE)
 	$(TOOLS)/genApps$(HOSTEXE) $@
 
diff --git a/src/ioc/bpt/RULES b/src/ioc/bpt/RULES
index 8b9ffe771..a434eb342 100644
--- a/src/ioc/bpt/RULES
+++ b/src/ioc/bpt/RULES
@@ -12,5 +12,5 @@
 # This is a Makefile fragment, see src/ioc/Makefile.
 
 $(patsubst %,$(COMMON_DIR)/%,$(BPT_DBD)) : \
-    $(COMMON_DIR)/bpt%.dbd : $(TOOLS)/makeBpt$(HOSTEXE)
+    $(COMMON_DIR)/bpt%.dbd : $(EPICS_BASE_HOST_BIN)/makeBpt$(HOSTEXE)
 
diff --git a/src/libCom/as/RULES b/src/libCom/as/RULES
index 9b6fa1bc5..a2a416f6e 100644
--- a/src/libCom/as/RULES
+++ b/src/libCom/as/RULES
@@ -16,6 +16,6 @@ asLib$(DEP): asLib_lex.c
 asLib.c: asLib_lex.c
 
 # Ensure that lexer and parser are built before they are needed
-asLib.c: $(TOOLS)/antelope$(HOSTEXE)
-asLib_lex.c: $(TOOLS)/e_flex$(HOSTEXE)
+asLib.c: $(EPICS_BASE_HOST_BIN)/antelope$(HOSTEXE)
+asLib_lex.c: $(EPICS_BASE_HOST_BIN)/e_flex$(HOSTEXE)
 asLib_lex.c: $(INSTALL_INCLUDE)/flex.skel.static
diff --git a/src/libCom/flex/RULES b/src/libCom/flex/RULES
index b4f4cbaf4..65406f4c5 100644
--- a/src/libCom/flex/RULES
+++ b/src/libCom/flex/RULES
@@ -10,4 +10,4 @@
 # This is a Makefile fragment, see src/libCom/Makefile.
 
 # Ensure that the lexer is built before it is needed
-parse.c: $(TOOLS)/antelope$(HOSTEXE)
+parse.c: $(EPICS_BASE_HOST_BIN)/antelope$(HOSTEXE)