diff --git a/src/tpm2/crypto/openssl/CryptPrimeSieve.c b/src/tpm2/crypto/openssl/CryptPrimeSieve.c
index 8c4e52b0..1e8cea10 100644
--- a/src/tpm2/crypto/openssl/CryptPrimeSieve.c
+++ b/src/tpm2/crypto/openssl/CryptPrimeSieve.c
@@ -215,6 +215,10 @@ FindNthSetBit(
     int          retValue;
     UINT32       sum = 0;
     BYTE         sel;
+
+    if (n < 1 || aSize < 1)			// libtpms added begin: Coverity 1550494
+        return -1;				// libtpms end
+
     //find the bit
     for(i = 0; (i < (int)aSize) && (sum < n); i++)
 	sum += BitsInByte(a[i]);