diff --git a/src/system/boot/libs/Jamfile b/src/system/boot/libs/Jamfile
index f35f3ceb8e..e9a26ea172 100644
--- a/src/system/boot/libs/Jamfile
+++ b/src/system/boot/libs/Jamfile
@@ -44,6 +44,8 @@ local libFDTSources =
 	fdt_overlay.c
 	;
 
+SubDirCcFlags -Wno-error=missing-prototypes ;
+
 local platform ;
 for platform in [ MultiBootSubDirSetup ] {
 	on $(platform) {
diff --git a/src/system/kernel/lib/zlib/Jamfile b/src/system/kernel/lib/zlib/Jamfile
index 237477f451..6cf33f7d17 100644
--- a/src/system/kernel/lib/zlib/Jamfile
+++ b/src/system/kernel/lib/zlib/Jamfile
@@ -4,6 +4,8 @@ local zlibSourceDirectory = [ BuildFeatureAttribute zlib : sources : path ] ;
 UseHeaders $(zlibSourceDirectory) ;
 UseHeaders $(zlibSourceDirectory) : true ;
 
+SubDirCcFlags -Wno-error=missing-prototypes ;
+
 local zlibSources =
 	adler32.c
 	crc32.c