diff --git a/ext/import-svg.cpp b/ext/import-svg.cpp
index a6b5476..2b14b7e 100644
--- a/ext/import-svg.cpp
+++ b/ext/import-svg.cpp
@@ -17,10 +17,11 @@ namespace msdfgen {
 #endif
 
 
-static bool readNodeType(char &output, const char *&pathDef) {
+static bool readNodeType(char &output, bool &haveInput, const char *&pathDef) {
     int shift;
     char nodeType;
-    if (sscanf(pathDef, " %c%n", &nodeType, &shift) == 1 && nodeType != '+' && nodeType != '-' && nodeType != '.' && nodeType != ',' && (nodeType < '0' || nodeType > '9')) {
+    haveInput = sscanf(pathDef, " %c%n", &nodeType, &shift) == 1;
+    if ( haveInput && nodeType != '+' && nodeType != '-' && nodeType != '.' && nodeType != ',' && (nodeType < '0' || nodeType > '9')) {
         pathDef += shift;
         output = nodeType;
         return true;
@@ -220,7 +221,8 @@ static Point2 handleArc(const char *&pathDef, char nodeType, Point2 prevNode, Co
 static bool buildFromPath(Shape &shape, const char *pathDef) {
     char nodeType;
     Point2 prevNode(0, 0);
-    while (readNodeType(nodeType, pathDef)) {
+    bool haveInput = pathDef && *pathDef;
+    while (haveInput && readNodeType(nodeType, haveInput, pathDef)) {
         Contour &contour = shape.addContour();
         bool contourStart = true;
 
@@ -228,7 +230,7 @@ static bool buildFromPath(Shape &shape, const char *pathDef) {
         Point2 controlPoint[2];
         Point2 node;
 
-        while (*pathDef) {
+        while (haveInput) {
             switch (nodeType) {
                 case 'M': case 'm':
                     REQUIRE(contourStart);
@@ -304,7 +306,7 @@ static bool buildFromPath(Shape &shape, const char *pathDef) {
             }
             contourStart &= nodeType == 'M' || nodeType == 'm';
             prevNode = node;
-            readNodeType(nodeType, pathDef);
+            readNodeType(nodeType, haveInput, pathDef);
         }
     NEXT_CONTOUR:;
     }