diff --git a/pkg/micro-ecc/Makefile b/pkg/micro-ecc/Makefile
index 237161a208..7bbf9aeda5 100644
--- a/pkg/micro-ecc/Makefile
+++ b/pkg/micro-ecc/Makefile
@@ -5,5 +5,11 @@ PKG_LICENSE=BSD-2-Clause
 
 include $(RIOTBASE)/pkg/pkg.mk
 
+# With LLVM register allocation fails. We can tell LLVM to spend more time
+# on trying to allocate registers using the following snippet:
+ifeq (llvm,$(TOOLCHAIN))
+  CFLAGS += -mllvm -exhaustive-register-search
+endif
+
 all:
 	$(QQ)"$(MAKE)" -C $(PKG_SOURCE_DIR) -f $(RIOTBASE)/Makefile.base
diff --git a/pkg/micro-ecc/Makefile.include b/pkg/micro-ecc/Makefile.include
index e63b996ddd..4d6987be64 100644
--- a/pkg/micro-ecc/Makefile.include
+++ b/pkg/micro-ecc/Makefile.include
@@ -4,8 +4,5 @@ CFLAGS += -Wno-unused-parameter
 CFLAGS += -Wno-unused-function
 CFLAGS += -Wno-unused-variable
 
-ifneq (,$(filter cortex-m0%,$(CPU_CORE)))
-  # LLVM/clang can't handle the inline assembler instructions on M0 in this
-  # package
-  TOOLCHAINS_BLACKLIST += llvm
-endif
+# llvm fails to allocate registers for inline assembly :/
+TOOLCHAINS_BLACKLIST += llvm