diff --git a/CMakeLists.txt b/CMakeLists.txt
index 5693ea9c..8362a46b 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -67,6 +67,7 @@ include(CheckFunctionExists)
 check_function_exists("gethostbyname" HAVE_GETHOSTBYNAME)
 check_function_exists("getaddrinfo" HAVE_GETADDRINFO)
 check_function_exists("gettimeofday" HAVE_GETTIMEOFDAY)
+check_function_exists("getpid" HAVE_GETPID)
 
 
 
diff --git a/configure.ac b/configure.ac
index f1b36fe4..81c18151 100644
--- a/configure.ac
+++ b/configure.ac
@@ -60,7 +60,7 @@ AC_CHECK_SIZEOF([long], 4)
 
 # Check headers/libs
 AC_CHECK_HEADERS([netdb.h])
-AC_CHECK_FUNCS([gethostbyname getaddrinfo gettimeofday inet_ntoa memset socket])
+AC_CHECK_FUNCS([gethostbyname getaddrinfo gettimeofday inet_ntoa memset socket getpid])
 AC_CHECK_LIB([network],[socket])
 
 # Thread local storage
diff --git a/src/tpm2_cryptocb.c b/src/tpm2_cryptocb.c
index 8753100f..c822efdb 100644
--- a/src/tpm2_cryptocb.c
+++ b/src/tpm2_cryptocb.c
@@ -120,6 +120,14 @@ int wolfTPM2_CryptoDevCb(int devId, wc_CryptoInfo* info, void* ctx)
         #endif
                 rc = exit_rc;
         }
+        else if (info->pk.type == WC_PK_TYPE_RSA_GET_SIZE) {
+            if (tlsCtx->rsaKey != NULL) {
+                *info->pk.rsa_get_size.keySize =
+                    tlsCtx->rsaKey->pub.publicArea.parameters.rsaDetail.keyBits
+                        / 8;
+                rc = 0;
+            }
+        }
         else if (info->pk.type == WC_PK_TYPE_RSA) {
             switch (info->pk.rsa.type) {
                 case RSA_PUBLIC_ENCRYPT:
@@ -153,6 +161,11 @@ int wolfTPM2_CryptoDevCb(int devId, wc_CryptoInfo* info, void* ctx)
                 case RSA_PRIVATE_DECRYPT:
                 {
                     /* private operations */
+                    if (tlsCtx->rsaKey == NULL) {
+                        /* TPM key not setup, fallback to software */
+                        rc = exit_rc;
+                        break;
+                    }
                     rc = wolfTPM2_RsaDecrypt(tlsCtx->dev, tlsCtx->rsaKey,
                         TPM_ALG_NULL, /* no padding */
                         info->pk.rsa.in, info->pk.rsa.inLen,
@@ -237,6 +250,11 @@ int wolfTPM2_CryptoDevCb(int devId, wc_CryptoInfo* info, void* ctx)
             word32 rsLen = sizeof(sigRS), keySz;
             word32 inlen = info->pk.eccsign.inlen;
 
+            if (tlsCtx->eccKey == NULL) {
+                /* TPM key not setup, fallback to software */
+                return exit_rc;
+            }
+
             /* get key size from wolf signing key */
             keySz = wc_ecc_size(info->pk.eccsign.key);
             if (keySz == 0) {