2 files changed, 4 insertions, 4 deletions
diff --git a/src/trace/siox.cpp b/src/trace/siox.cpp
index f06f943e0..c69af04a1 100644
--- a/src/trace/siox.cpp
+++ b/src/trace/siox.cpp
@@ -884,7 +884,7 @@ SioxImage Siox::extractForeground(const SioxImage &originalImage,
         return workImage;
         }
 
-    trace("knownBg:%d knownFg:%d", knownBg.size(), knownFg.size());
+    trace("knownBg:%zu knownFg:%zu", knownBg.size(), knownFg.size());
 
 
     std::vector<CieLab> bgSignature ;
diff --git a/src/trace/siox.h b/src/trace/siox.h
index 8f6f90ff9..5d6059d3c 100644
--- a/src/trace/siox.h
+++ b/src/trace/siox.h
@@ -374,7 +374,7 @@ private:
     /**
      * Error logging
      */
-    void error(char *fmt, ...);
+    void error(char *fmt, ...) G_GNUC_PRINTF(2,3);
 
 };
 
@@ -562,12 +562,12 @@ private:
     /**
      * Error logging
      */
-    void error(char *fmt, ...);
+    void error(char *fmt, ...) G_GNUC_PRINTF(2,3);
 
     /**
      * Trace logging
      */
-    void trace(char *fmt, ...);
+    void trace(char *fmt, ...) G_GNUC_PRINTF(2,3);
 
     /**
      *  Stage 1 of the color signature work.  'dims' will be either