diff --git a/src/Makevars b/src/Makevars
index ddd09a72..b067584f 100755
--- a/src/Makevars
+++ b/src/Makevars
@@ -1,6 +1,6 @@
 STANHEADERS_SRC = `"$(R_HOME)/bin$(R_ARCH_BIN)/Rscript" --vanilla -e "cat(system.file('include', 'src', package = 'StanHeaders'))"`
 CXX_STD = CXX14
-PKG_CPPFLAGS = -I"../inst/include" -I"$(STANHEADERS_SRC)" -DBOOST_DISABLE_ASSERTS -DBOOST_PHOENIX_NO_VARIADIC_EXPRESSION
+PKG_CPPFLAGS = -I"../src/include" -I"$(STANHEADERS_SRC)" -DBOOST_DISABLE_ASSERTS -DBOOST_PHOENIX_NO_VARIADIC_EXPRESSION
 SHLIB_LDFLAGS = $(SHLIB_CXXLDFLAGS)
 SHLIB_LD = $(SHLIB_CXXLD)
 
diff --git a/src/Makevars.win b/src/Makevars.win
index 743ffeed..52df40c2 100755
--- a/src/Makevars.win
+++ b/src/Makevars.win
@@ -1,5 +1,5 @@
 STANHEADERS_SRC = `"$(R_HOME)/bin$(R_ARCH_BIN)/Rscript" --vanilla -e "cat(system.file('include', 'src', package = 'StanHeaders'))"`
 CXX_STD = CXX14
-PKG_CPPFLAGS = -I"../inst/include" -I"$(STANHEADERS_SRC)" -DBOOST_DISABLE_ASSERTS -DBOOST_PHOENIX_NO_VARIADIC_EXPRESSION
+PKG_CPPFLAGS = -I"../src/include" -I"$(STANHEADERS_SRC)" -DBOOST_DISABLE_ASSERTS -DBOOST_PHOENIX_NO_VARIADIC_EXPRESSION
 SHLIB_LDFLAGS = $(SHLIB_CXXLDFLAGS)
 SHLIB_LD = $(SHLIB_CXXLD)