diff --git a/package/assimp/assimp.mk b/package/assimp/assimp.mk
index 08893fff00..298e121cb8 100644
--- a/package/assimp/assimp.mk
+++ b/package/assimp/assimp.mk
@@ -16,6 +16,14 @@ ifeq ($(BR2_m68k),y)
 ASSIMP_CXXFLAGS += -mxgot
 endif
 
+# workaround SuperH compiler failure when static linking (i.e -fPIC is
+# not passed) in gcc versions 5.x or older. The -Os optimization level
+# causes a "unable to find a register to spill in class
+# ‘GENERAL_REGS’" error. -O2 works fine.
+ifeq ($(BR2_sh):$(BR2_STATIC_LIBS):$(BR2_HOST_GCC_AT_LEAST_6),y:y:)
+ASSIMP_CXXFLAGS += -O2
+endif
+
 ASSIMP_CONF_OPTS += -DASSIMP_BUILD_TESTS=OFF \
 	-DCMAKE_CXX_FLAGS="$(TARGET_CXXFLAGS) $(ASSIMP_CXXFLAGS)"