diff --git a/srcpkgs/mozjs52/template b/srcpkgs/mozjs52/template
index 6fe724080a2..2d6489bcc84 100644
--- a/srcpkgs/mozjs52/template
+++ b/srcpkgs/mozjs52/template
@@ -20,6 +20,9 @@ CFLAGS="-fpermissive -fno-delete-null-pointer-checks -fno-tree-vrp -fno-strict-a
 CXXFLAGS="-fpermissive -fno-delete-null-pointer-checks -fno-tree-vrp -fno-strict-aliasing"
 # Use BFD linker to avoid erroneous detection of llvm pr8927 with *-musl
 LDFLAGS="-fuse-ld=bfd"
+# Flags for gcc9.1
+CFLAGS+=" -Wno-format-overflow"
+CXXFLAGS+=" -Wno-format-overflow"
 
 case "$XBPS_TARGET_MACHINE" in
 	mips*|armv[56]*|ppc|ppc-musl) makedepends+=" libatomic-devel" ; LDFLAGS+=" -latomic" ;;