diff --git a/src/DrawingTracer.cc b/src/DrawingTracer.cc
index 24fa6e2..05ab81b 100644
--- a/src/DrawingTracer.cc
+++ b/src/DrawingTracer.cc
@@ -13,7 +13,7 @@
 namespace pdf2htmlEX
 {
 
-DrawingTracer::DrawingTracer(const Param & param):param(param)
+DrawingTracer::DrawingTracer(const Param & param): param(param), cairo(nullptr)
 {
 }
 
diff --git a/src/DrawingTracer.h b/src/DrawingTracer.h
index d8cee1c..a04b453 100644
--- a/src/DrawingTracer.h
+++ b/src/DrawingTracer.h
@@ -63,7 +63,7 @@ private:
     void transform_bbox_by_ctm(double * bbox);
 
     const Param & param;
-    cairo_t * cairo = nullptr;
+    cairo_t * cairo;
 };
 
 } /* namespace pdf2htmlEX */
diff --git a/src/HTMLState.h b/src/HTMLState.h
index 9327e5c..195af21 100644
--- a/src/HTMLState.h
+++ b/src/HTMLState.h
@@ -63,8 +63,10 @@ struct HTMLLineState
     double x,y;
     double transform_matrix[4];
     // The page-cope char index(in drawing order) of the first char in this line.
-    int first_char_index = -1;
-    const std::vector<bool> * chars_covered = nullptr;
+    int first_char_index;
+    const std::vector<bool> * chars_covered;
+
+    HTMLLineState(): first_char_index(-1), chars_covered(nullptr) { }
 };
 
 struct HTMLClipState