diff --git a/src/libs/png/Jamfile b/src/libs/png/Jamfile
index 559762e0b5..f63407c083 100644
--- a/src/libs/png/Jamfile
+++ b/src/libs/png/Jamfile
@@ -2,7 +2,7 @@ SubDir OBOS_TOP src libs png ;
 
 UseLibraryHeaders zlib ;
 
-SharedLibrary png : 
+local shared_files = 
 	png.c
 	pngerror.c
 	pnggccrd.c
@@ -20,25 +20,10 @@ SharedLibrary png :
 	pngwrite.c
 	pngwtran.c
 	pngwutil.c
-: z ;
-
-StaticLibrary png : 
-	png.c
-	pngerror.c
-	pnggccrd.c
-	pngget.c
-	pngmem.c
-	pngpread.c
-	pngread.c
-	pngrio.c
-	pngrtran.c
-	pngrutil.c
-	pngset.c
-	pngtrans.c
-	pngvcrd.c
-	pngwio.c
-	pngwrite.c
-	pngwtran.c
-	pngwutil.c
-: STATIC_LIBRARY_DIR
 ;
+
+Objects $(shared_files) ;
+
+SharedLibrary png : [ FGristFiles $(shared_files:S=.o) ] : z ;
+
+StaticLibrary png : [ FGristFiles $(shared_files:S=.o) ] : STATIC_LIBRARY_DIR ;
diff --git a/src/libs/zlib/Jamfile b/src/libs/zlib/Jamfile
index de337b935a..3afebc5c21 100644
--- a/src/libs/zlib/Jamfile
+++ b/src/libs/zlib/Jamfile
@@ -2,7 +2,7 @@ SubDir OBOS_TOP src libs zlib ;
 
 UseLibraryHeaders zlib ;
 
-SharedLibrary z : 
+local shared_files =
 	adler32.c
 	compress.c
 	crc32.c
@@ -17,19 +17,9 @@ SharedLibrary z :
 	zutil.c
 ;
 
-StaticLibrary z : 
-	adler32.c
-	compress.c
-	crc32.c
-	deflate.c
-	gzio.c
-	infback.c
-	inffast.c
-	inflate.c
-	inftrees.c
-	trees.c
-	uncompr.c
-	zutil.c
-: STATIC_LIBRARY_DIR
-;
+Objects $(shared_files) ;
+
+SharedLibrary z : [ FGristFiles $(shared_files:S=.o) ] ;
+
+StaticLibrary z : [ FGristFiles $(shared_files:S=.o) ] : STATIC_LIBRARY_DIR ;