diff --git a/code/B3D/B3DImporter.cpp b/code/B3D/B3DImporter.cpp
index b483ed752..f887da8d8 100644
--- a/code/B3D/B3DImporter.cpp
+++ b/code/B3D/B3DImporter.cpp
@@ -146,7 +146,7 @@ AI_WONT_RETURN void B3DImporter::Oops(){
 // ------------------------------------------------------------------------------------------------
 AI_WONT_RETURN void B3DImporter::Fail( string str ){
 #ifdef DEBUG_B3D
-    ASSIMP_LOG_ERROR_F("Error in B3D file data: %s", str.c_str());
+    ASSIMP_LOG_ERROR_F("Error in B3D file data: ", str);
 #endif
     throw DeadlyImportError( "B3D Importer - error in B3D file data: "+str );
 }
@@ -226,7 +226,7 @@ string B3DImporter::ReadChunk(){
         tag+=char( ReadByte() );
     }
 #ifdef DEBUG_B3D
-    ASSIMP_LOG_DEBUG_F("ReadChunk: %s", tag.c_str());
+    ASSIMP_LOG_DEBUG_F("ReadChunk: ", tag);
 #endif
     unsigned sz=(unsigned)ReadInt();
     _stack.push_back( _pos+sz );
@@ -386,7 +386,7 @@ void B3DImporter::ReadTRIS(int v0) {
 		matid = 0;
 	} else if (matid < 0 || matid >= (int)_materials.size()) {
 #ifdef DEBUG_B3D
-		ASSIMP_LOG_ERROR_F("material id=%d", matid);
+		ASSIMP_LOG_ERROR_F("material id=", matid);
 #endif
 		Fail("Bad material id");
 	}
@@ -406,7 +406,7 @@ void B3DImporter::ReadTRIS(int v0) {
 		int i2 = ReadInt() + v0;
 		if (i0 < 0 || i0 >= (int)_vertices.size() || i1 < 0 || i1 >= (int)_vertices.size() || i2 < 0 || i2 >= (int)_vertices.size()) {
 #ifdef DEBUG_B3D
-			ASSIMP_LOG_ERROR_F("Bad triangle index: i0=%d, i1=%d, i2=%d", i0, i1, i2);
+			ASSIMP_LOG_ERROR_F("Bad triangle index: i0=", i0, ", i1=", i1, ", i2=", i2);
 #endif
 			Fail("Bad triangle index");
 			continue;
diff --git a/code/FBX/FBXConverter.cpp b/code/FBX/FBXConverter.cpp
index 1956c3fb4..268988f82 100644
--- a/code/FBX/FBXConverter.cpp
+++ b/code/FBX/FBXConverter.cpp
@@ -1597,11 +1597,11 @@ namespace Assimp {
             aiBone *bone = nullptr;
 
             if (bone_map.count(deformer_name)) {
-                ASSIMP_LOG_DEBUG_F("retrieved bone from lookup %s. Deformer:%s", bone_name.C_Str(), deformer_name.c_str());
-                bone = bone_map[deformer_name];
-            } else {
-                ASSIMP_LOG_DEBUG_F("created new bone %s. Deformer: %s", bone_name.C_Str(), deformer_name.c_str());
-                bone = new aiBone();
+				ASSIMP_LOG_DEBUG_F("retrieved bone from lookup ", bone_name.C_Str(), ". Deformer:", deformer_name);
+				bone = bone_map[deformer_name];
+			} else {
+				ASSIMP_LOG_DEBUG_F("created new bone ", bone_name.C_Str(), ". Deformer: ", deformer_name);
+				bone = new aiBone();
                 bone->mName = bone_name;
 
                 // store local transform link for post processing
@@ -1647,7 +1647,7 @@ namespace Assimp {
                 bone_map.insert(std::pair<const std::string, aiBone *>(deformer_name, bone));
             }
 
-            ASSIMP_LOG_DEBUG_F("bone research: Indicies size: %zu", out_indices.size());
+            ASSIMP_LOG_DEBUG_F("bone research: Indicies size: ", out_indices.size());
 
             // lookup must be populated in case something goes wrong
             // this also allocates bones to mesh instance outside
diff --git a/include/assimp/LineSplitter.h b/include/assimp/LineSplitter.h
index 271b321cc..2fa61cba7 100644
--- a/include/assimp/LineSplitter.h
+++ b/include/assimp/LineSplitter.h
@@ -72,7 +72,7 @@ for(LineSplitter splitter(stream);splitter;++splitter) {
        if (strtol(splitter[2]) > 5) { .. }
     }
 
-    ASSIMP_LOG_DEBUG_F("Current line is: %zu", splitter.get_index());
+    ASSIMP_LOG_DEBUG_F("Current line is: ", splitter.get_index());
 }
 @endcode
 */