diff --git a/tools/tpm/Makefile b/tools/tpm/Makefile
index 62e09b361..4ac391ab2 100644
--- a/tools/tpm/Makefile
+++ b/tools/tpm/Makefile
@@ -14,6 +14,7 @@ WOLFDIR = $(WOLFBOOTDIR)/lib/wolfssl/
 WOLFTPMDIR = $(WOLFBOOTDIR)/lib/wolfTPM/
 CFLAGS = -Wall -Wextra -Werror
 CFLAGS += -DWOLFSSL_USER_SETTINGS -DWOLFTPM_USER_SETTINGS -DWOLFBOOT_TPM -DHAVE_NETDB_H
+CFLAGS += -DXSTRTOL=strtol
 CFLAGS += -I. -I$(WOLFDIR) -I$(WOLFTPMDIR) -I$(WOLFBOOTDIR)/include
 LDFLAGS =
 OBJDIR = ./