diff -Nurd g2clib-1.6.3.orig/grib2c.pc.in g2clib-1.6.3/grib2c.pc.in
--- g2clib-1.6.3.orig/grib2c.pc.in	2021-06-22 02:10:52.000000000 -0400
+++ g2clib-1.6.3/grib2c.pc.in	2021-06-22 02:33:18.000000000 -0400
@@ -5,7 +5,7 @@
 
 Name: glib2c
 Description: NCEP GRIB2 encoder/decoder library
-Requires: libpng
+Requires: 
 Version: 1.6.0
 Libs: -lgrib2c
-Libs.private: -lgrib2c -lpng16 -lopenjp2
+Libs.private: 
diff -Nurd g2clib-1.6.3.orig/makefile g2clib-1.6.3/makefile
--- g2clib-1.6.3.orig/makefile	2021-06-22 02:10:52.000000000 -0400
+++ g2clib-1.6.3/makefile	2021-06-22 02:44:54.000000000 -0400
@@ -10,14 +10,14 @@
 #
 #  In addition, INC must include all directories where the above
 #  mentioned include files can be found.
-DEFS=-DUSE_JPEG2000 -DUSE_PNG
+DEFS=-DUSE_JPEG2000 -DUSE_PNG -MD
 
 #
 # Please make sure to include all idirectories where include files  
 #     can be found (jasper/*.h and png.h pngconf.h zconf.h zlib.h)
 #
 
-#INC=-I/nwprod/lib/include/
+INC=$(CPPFLAGS) `pkg-config --cflags libpng`
 
 #
 #   This "C" source code contains many uses of the C++
@@ -31,9 +31,9 @@
 PIC:= -fPIC
 
 prefix=/usr
-LIBDIR=/usr/lib
-SHLIB=libgrib2c.so.0d
-SONAME=libgrib2c.so.0d
+LIBDIR=$(prefix)/lib
+SHLIB=libgrib2c.dylib
+SONAME=libgrib2c.0d.dylib
 
 CC=gcc
 
@@ -105,17 +105,19 @@
 	 seekgb.o
 
 
-all: $(LIB) $(SHLIB)
+all: $(SHLIB) grib2c.pc
 
 $(SHLIB): $(OBJS)
-	gcc $(LDFLAGS) -Wl,-as-needed -shared  -o $(SHLIB) -Wl,-soname,$(SONAME) $(OBJS) $(LIBS)
+	gcc $(LDFLAGS) -dynamiclib  -o $(SONAME) -install_name $(LIBDIR)/$(SONAME) $(OBJS) $(LIBS)
+	ln -s $(SONAME) $(SHLIB)
 
 grib2c.pc: grib2c.pc.in
-	cat grib2c.pc.in | sed -e 's!@prefix@!${PREFIX}!' | sed -e 's!@libdir@!${LIBDIR}!' > grib2c.pc
+	cat grib2c.pc.in | sed -e 's!@prefix@!${prefix}!' | sed -e 's!@libdir@!${LIBDIR}!' > grib2c.pc
 
-install: $(LIB) $(SHLIB) grib2c.pc
+install: $(SHLIB) grib2c.pc
 	mkdir -p $(LIBDIR)
-	cp $(LIB) $(SHLIB) $(LIBDIR)
+	cp $(SONAME) $(LIBDIR)
+	ln -s $(SONAME) $(LIBDIR)/$(SHLIB)
 	mkdir -p $(LIBDIR)/pkgconfig
 	cp grib2c.pc $(LIBDIR)/pkgconfig
 	mkdir -p $(prefix)/include