diff --git a/lib/src/clixon_xml_diff.c b/lib/src/clixon_xml_diff.c
index fddc7c308..e94928204 100644
--- a/lib/src/clixon_xml_diff.c
+++ b/lib/src/clixon_xml_diff.c
@@ -539,7 +539,7 @@ xml_diff(cxobj     *x0,
         goto ok;
     }
     if (x0 == NULL){
-        if (cxvec_append(x0, second, secondlen) < 0)
+        if (cxvec_append(x1, second, secondlen) < 0)
             goto done;
         goto ok;
     }
diff --git a/lib/src/clixon_xpath_eval.c b/lib/src/clixon_xpath_eval.c
index d181d84cf..c8677412c 100644
--- a/lib/src/clixon_xpath_eval.c
+++ b/lib/src/clixon_xpath_eval.c
@@ -763,7 +763,9 @@ xp_numop(xp_ctx    *xc1,
             xr->xc_number = n1/n2;
             break;
         case XO_MOD:
-            xr->xc_number = ((int)n1)%((int)n2);
+            /* XPath 1.0 3.5: remainder from a truncating division, as fmod().
+             * Integer % crashes with SIGFPE if n2 truncates to 0 */
+            xr->xc_number = fmod(n1, n2);
             break;
         case XO_ADD:
             xr->xc_number = n1+n2;
diff --git a/test/test_xpath.sh b/test/test_xpath.sh
index 1fa2632ed..039735424 100755
--- a/test/test_xpath.sh
+++ b/test/test_xpath.sh
@@ -412,6 +412,25 @@ expectpart "$($clixon_util_xpath -D $DBG -f $xml2 -p "string-length(\"12345\")")
 new "xpath string-length path"
 expectpart "$($clixon_util_xpath -D $DBG -f $xml2 -p "string-length(aaa/name)")" 0 "number:3"
 
+# mod: XPath 1.0 3.5, remainder from a truncating division
+new "xpath 5 mod 2"
+expectpart "$($clixon_util_xpath -D $DBG -f $xml2 -p "5 mod 2")" 0 "number:1.0"
+
+new "xpath 5 mod -2"
+expectpart "$($clixon_util_xpath -D $DBG -f $xml2 -p "5 mod -2")" 0 "number:1.0"
+
+new "xpath -5 mod 2"
+expectpart "$($clixon_util_xpath -D $DBG -f $xml2 -p "-5 mod 2")" 0 "number:-1.0"
+
+new "xpath 5.5 mod 2"
+expectpart "$($clixon_util_xpath -D $DBG -f $xml2 -p "5.5 mod 2")" 0 "number:1.5"
+
+new "xpath 1 mod 0 is NaN, not crash"
+expectpart "$($clixon_util_xpath -D $DBG -f $xml2 -p "1 mod 0")" 0 "number:" "nan"
+
+new "xpath 1 mod 0.5, divisor truncated to int was 0"
+expectpart "$($clixon_util_xpath -D $DBG -f $xml2 -p "1 mod 0.5")" 0 "number:0.0"
+
 # translate
 new "xpath translate" # modified
 expectpart "$($clixon_util_xpath -D $DBG -f $xml2 -p "translate(\"bar\", \"abc\",\"DEF\")")" 0 "string:EDr$"