diff --git a/configure.ac b/configure.ac
index 05e8a1e..2dcde81 100644
--- a/configure.ac
+++ b/configure.ac
@@ -17,16 +17,5 @@ CXXFLAGS=`"${R_HOME}/bin/R" CMD config CXXFLAGS`
 CPPFLAGS=`"${R_HOME}/bin/R" CMD config CPPFLAGS`
 LDFLAGS=`"${R_HOME}/bin/R" CMD config LDFLAGS`
 
-# Checks for libraries.
-ZLIB_FLAGS="-Izlib"
-ZLIB_OBJECTS=`ls -1 src/zlib/*.c | sed 's/^src\///' | sed 's/\\.c$/\\.o/'`
-AC_SEARCH_LIBS([inflate], [z], [
-    ZLIB_FLAGS=""
-    ZLIB_OBJECTS=""
-])
-
-AC_SUBST(ZLIB_FLAGS)
-AC_SUBST(ZLIB_OBJECTS)
-
 AC_CONFIG_FILES([src/Makevars])
 AC_OUTPUT
diff --git a/src/Makevars.in b/src/Makevars.in
index 77da572..358cc1d 100644
--- a/src/Makevars.in
+++ b/src/Makevars.in
@@ -1,5 +1,5 @@
-PKG_CPPFLAGS = -DNDEBUG -DHAVE_ZLIB -DUSING_R -DRNIFTI_NIFTILIB_DEDUPLICATE -I../inst/include @ZLIB_FLAGS@
+PKG_CPPFLAGS = -DNDEBUG -DHAVE_ZLIB -DUSING_R -DRNIFTI_NIFTILIB_DEDUPLICATE -I../inst/include
 PKG_LIBS = @LIBS@
 
 NIFTI_OBJECTS = znzlib/znzlib.o niftilib/nifti1_io.o niftilib/nifti2_io.o
-OBJECTS = main.o zzz.o @ZLIB_OBJECTS@ $(NIFTI_OBJECTS)
+OBJECTS = main.o zzz.o $(NIFTI_OBJECTS)