diff --git a/src/sapB_fmt_plug.c b/src/sapB_fmt_plug.c
index 6a906b0d74..c10e9a9494 100644
--- a/src/sapB_fmt_plug.c
+++ b/src/sapB_fmt_plug.c
@@ -661,7 +661,7 @@ static int crypt_all(int *pcount, struct db_salt *salt)
 			keyLen[t] = strlen(saved_plain[t]);
 
 			// Back-out of trailing spaces
-			while ( saved_plain[t][keyLen[t] - 1] == ' ' )
+			while ( keyLen[t] && saved_plain[t][keyLen[t] - 1] == ' ' )
 			{
 				if (keyLen[t] == 0) break;
 				saved_plain[t][--keyLen[t]] = 0;
diff --git a/src/sapG_fmt_plug.c b/src/sapG_fmt_plug.c
index 72a0ce6ac2..e282d25dd0 100644
--- a/src/sapG_fmt_plug.c
+++ b/src/sapG_fmt_plug.c
@@ -666,7 +666,7 @@ static int crypt_all(int *pcount, struct db_salt *salt)
 			keyLen[index] = strlen((char*)saved_key[index]);
 
 			// Back-out of trailing spaces
-			while (saved_key[index][keyLen[index] - 1] == ' ') {
+			while (keyLen[index] && saved_key[index][keyLen[index] - 1] == ' ') {
 				saved_key[index][--keyLen[index]] = 0;
 				if (keyLen[index] == 0) break;
 			}