diff --git a/rtexif/canonattribs.cc b/rtexif/canonattribs.cc
index 5c27cb56b..a1568d85f 100644
--- a/rtexif/canonattribs.cc
+++ b/rtexif/canonattribs.cc
@@ -53,7 +53,9 @@ class CAApertureInterpreter : public Interpreter {
         CAApertureInterpreter () {}
         virtual std::string toString (Tag* t) {
         	char buffer[32];
-            sprintf (buffer, "%0.1f", pow(2.0, t->toDouble()/64.0));
+        	double v = pow(2.0, t->toDouble()/64.0);
+        	if( v<0. || v> 1000.) return "undef";
+            sprintf (buffer, "%.1f",v );
             return buffer;
         }
 };
@@ -74,7 +76,7 @@ public:
     	int sec = t->toInt(0,SHORT);
     	if( !sec ) return "OFF";
     	char buffer[32];
-        sprintf (buffer, "%0.1fs %s", sec/10., sec&0x4000?",Custom":"");
+        sprintf (buffer, "%.1fs %s", sec/10., sec&0x4000?",Custom":"");
         return buffer;
     }
 };
@@ -392,9 +394,11 @@ class CAFocalInterpreter : public Interpreter {
 public:
     virtual std::string toString (Tag* t) {
     	Tag *unitTag = t->getParent()->getRoot()->findTag("FocalUnits");
-    	double unit = unitTag->toDouble();
+    	double v = unitTag?unitTag->toDouble():1.;
+    	v = (v>0. ? t->toDouble()/v : t->toDouble());
+    	if( v <0. || v>1000000.) return "undef";
     	char buffer[32];
-        sprintf (buffer, "%0.1f", (unit>0. ? t->toDouble()/unit : t->toDouble()));
+        sprintf (buffer, "%.1f", v );
         return buffer;
     }
 };
@@ -741,8 +745,8 @@ public:
 	virtual std::string toString (Tag* t) {
 		int val = t->toInt();
 		if( val <40 ) return "undef";
-    	char buffer[32];
-        sprintf (buffer, "%0.2fmm", val *25.4 / 1000);
+    	char buffer[1024];
+        sprintf (buffer, "%.2fmm", val *25.4 / 1000);
         return buffer;
 	}
 };
@@ -751,8 +755,9 @@ CAFocalPlaneInterpreter caFocalPlaneInterpreter;
 class CAExposureTimeInterpreter : public Interpreter {
 public:
 	virtual std::string toString (Tag* t) {
-    	char buffer[32];
-        sprintf (buffer, "%0.3f", pow (2, - t->toInt()/32.0) );
+    	char buffer[1024];
+    	double d = pow (2, - t->toInt()/32.0);
+        sprintf (buffer, "%.3f", d);
         return buffer;
 	}
 };
@@ -760,8 +765,8 @@ CAExposureTimeInterpreter caExposureTimeInterpreter;
 
 class CAEVInterpreter : public Interpreter {
 	virtual std::string toString (Tag* t) {
-    	char buffer[32];
-        sprintf (buffer, "%0.1f", t->toDouble()/32.0  );
+    	char buffer[1024];
+        sprintf (buffer, "%.1f", t->toDouble()/32.0  );
         return buffer;
 	}
 };
@@ -770,8 +775,8 @@ CAEVInterpreter caEVInterpreter;
 class CABaseISOInterpreter : public Interpreter {
 public:
 	virtual std::string toString (Tag* t) {
-    	char buffer[32];
-        sprintf (buffer, "%0.0f", pow (2, t->toInt()/32.0 - 4) * 50 );
+    	char buffer[1024];
+        sprintf (buffer, "%.0f", pow (2, t->toInt()/32.0 - 4) * 50 );
         return buffer;
 	}
 };
@@ -865,7 +870,7 @@ public:
 		int n= t->toInt();
 		if( n==-1) return "undef";
 	    char buffer[32];
-        sprintf (buffer, "%0.f", n/32. );
+        sprintf (buffer, "%.0f", n/32. );
         return buffer;
 	}
 };
@@ -911,8 +916,8 @@ CAControModeInterpreter caControModeInterpreter;
 class CAFocusDistanceInterpreter : public Interpreter {
 public:
 	virtual std::string toString (Tag* t) {
-    	char buffer[32];
-        sprintf (buffer, "%0.2f", t->toDouble()/100 );
+    	char buffer[1024];
+        sprintf (buffer, "%.2f", t->toDouble()/100 );
         return buffer;
 	}
 };
@@ -921,8 +926,8 @@ CAFocusDistanceInterpreter caFocusDistanceInterpreter;
 class CAMeasuredEVInterpreter : public Interpreter {
 public:
 	virtual std::string toString (Tag* t) {
-    	char buffer[32];
-        sprintf (buffer, "%0.1f", t->toDouble()/8 - 6 );
+    	char buffer[1024];
+        sprintf (buffer, "%.1f", t->toDouble()/8 - 6 );
         return buffer;
 	}
 };
diff --git a/rtexif/pentaxattribs.cc b/rtexif/pentaxattribs.cc
index 403f836c7..f5e0a9f3a 100644
--- a/rtexif/pentaxattribs.cc
+++ b/rtexif/pentaxattribs.cc
@@ -233,7 +233,9 @@ public:
 	PAFNumberInterpreter () {}
     virtual std::string toString (Tag* t) {
     	char buffer[32];
-        sprintf (buffer, "%0.1f", t->toDouble()/10);
+    	double v = t->toDouble()/10;
+    	if( v < 0. || v > 1000. ) return "undef";
+        sprintf (buffer, "%.1f", v );
         return buffer;
     }
 };
@@ -709,7 +711,9 @@ class PAMaxApertureInterpreter: public Interpreter {
     	   a &= 0x7F;
     	   if(a>1){
     		  char buffer[32];
-              sprintf (buffer, "%0.1f", pow(2.0, (a-1)/32.0));
+    		  double v = pow(2.0, (a-1)/32.0);
+    		  if( v < 0. || v > 1000. ) return "undef";
+              sprintf (buffer, "%.1f", v );
               return buffer;
     	   }else
     		  return "n/a";
@@ -725,7 +729,7 @@ public:
  	   int a = t->toInt(0,BYTE);
  	   int mina = a & 0x0F;
  	   int maxa = (a & 0xF0)>>4;
-       sprintf (buffer, "%0.1f - %0.0f", pow(2.0, maxa/4.0), pow(2.0, (mina+10)/4.0));
+       sprintf (buffer, "%.1f - %.0f", pow(2.0, maxa/4.0), pow(2.0, (mina+10)/4.0));
        return buffer;
 
     }
@@ -820,9 +824,9 @@ class PAExternalFlashGNInterpreter: public Interpreter {
 	public:
 	PAExternalFlashGNInterpreter(){}
 	virtual std::string toString (Tag* t) {
-		   char buffer[32];
+		   char buffer[1024];
 	       int b = t->toInt(0,BYTE) & 0x1F;
-	       sprintf (buffer, "%0.0f", pow(2.,b/16.+4) );
+	       sprintf (buffer, "%.0f", pow(2.,b/16.+4) );
 	       return buffer;
 	}
 };
diff --git a/rtexif/rtexif.cc b/rtexif/rtexif.cc
index 93f0b9aab..51a66c93d 100644
--- a/rtexif/rtexif.cc
+++ b/rtexif/rtexif.cc
@@ -809,7 +809,7 @@ void Tag::toString (char* buffer, int ofs) {
       }
   }
   else if (type==ASCII) {
-    sprintf (buffer, "%s", value+ofs);
+    sprintf (buffer, "%.64s", value+ofs);
     return; 
   }
 
@@ -828,8 +828,8 @@ void Tag::toString (char* buffer, int ofs) {
         case BYTE:  sprintf (b, "%d", value[i+ofs]); break;
         case SSHORT: sprintf (b, "%d", toInt(2*i+ofs)); break;
         case SHORT: sprintf (b, "%u", toInt(2*i+ofs)); break;
-        case SLONG: sprintf (b, "%ld", toInt(4*i+ofs)); break;
-        case LONG:  sprintf (b, "%lu", toInt(4*i+ofs)); break;
+        case SLONG: sprintf (b, "%ld", (long)toInt(4*i+ofs)); break;
+        case LONG:  sprintf (b, "%lu", (unsigned long)toInt(4*i+ofs)); break;
         case SRATIONAL: 
         case RATIONAL: sprintf (b, "%d/%d", (int)sget4 (value+8*i+ofs, getOrder()), (int)sget4 (value+8*i+ofs+4, getOrder())); break; 
         case FLOAT:    sprintf (b, "%g", toDouble(8*i+ofs)); break;
@@ -841,7 +841,7 @@ void Tag::toString (char* buffer, int ofs) {
 
 std::string Tag::nameToString (int i) {
 
-    static char buffer[1024];
+    char buffer[1024];
     if (attrib) 
         strcpy (buffer, attrib->name);
     else 
@@ -853,7 +853,7 @@ std::string Tag::nameToString (int i) {
 
 std::string Tag::valueToString () {
 
-    static char buffer[1024];
+    char buffer[1024];
     if (attrib && attrib->interpreter) 
         return attrib->interpreter->toString (this);
     else {
@@ -1107,7 +1107,7 @@ Tag* ExifManager::saveCIFFMNTag (FILE* f, TagDirectory* root, int len, const cha
 
 void ExifManager::parseCIFF (FILE* f, int base, int length, TagDirectory* root) {
 
-  static char buffer[1024];
+  char buffer[1024];
   Tag* t;
 
   fseek (f, base+length-4, SEEK_SET);
diff --git a/rtexif/stdattribs.cc b/rtexif/stdattribs.cc
index 053991c5a..3e88af92f 100644
--- a/rtexif/stdattribs.cc
+++ b/rtexif/stdattribs.cc
@@ -244,7 +244,9 @@ class FNumberInterpreter : public Interpreter {
         FNumberInterpreter () {}
         virtual std::string toString (Tag* t) {
         	char buffer[32];
-            sprintf (buffer, "%0.1f", t->toDouble());
+        	double v = t->toDouble();
+        	if( v < 0. || v > 1000. ) return "undef";
+            sprintf (buffer, "%0.1f", v);
             return buffer;
         }
 };
@@ -255,7 +257,9 @@ class ApertureInterpreter : public Interpreter {
         ApertureInterpreter () {}
         virtual std::string toString (Tag* t) {
         	char buffer[32];
-            sprintf (buffer, "%0.1f", pow(2.0, t->toDouble()/2.0));
+        	double v = pow(2.0, t->toDouble()/2.0);
+        	if( v < 0. || v > 1000. ) return "undef";
+            sprintf (buffer, "%.1f", v );
             return buffer;
         }
 };
@@ -266,7 +270,9 @@ class ExposureBiasInterpreter : public Interpreter {
         ExposureBiasInterpreter () {}
         virtual std::string toString (Tag* t) {
         	char buffer[32];
-            sprintf (buffer, "%+0.2f", t->toDouble());
+        	double v = t->toDouble();
+        	if( v < -1000. || v > 1000. ) return "undef";
+            sprintf (buffer, "%+0.2f", v );
             return buffer;
         }
 };
@@ -276,12 +282,12 @@ class ShutterSpeedInterpreter : public Interpreter {
     public:
         ShutterSpeedInterpreter () {}
         virtual std::string toString (Tag* t) {
-        	char buffer[32];
+        	char buffer[1024];
             double d = pow (2.0, -t->toDouble());
             if (d > 0.0 && d < 0.9)
-                sprintf (buffer, "1/%0.0f", 1.0 / d);
+                sprintf (buffer, "1/%.0f", 1.0 / d);
             else
-                sprintf (buffer, "%0.1f", d);
+                sprintf (buffer, "%.1f", d);
             return buffer;
         }
 };
@@ -291,12 +297,12 @@ class ExposureTimeInterpreter : public Interpreter {
     public:
         ExposureTimeInterpreter () {}
         virtual std::string toString (Tag* t) {
-        	char buffer[32];
+        	char buffer[1024];
             double d = t->toDouble();
             if (d > 0.0 && d < 0.9)
-                sprintf (buffer, "1/%0.0f", 1.0 / d);
+                sprintf (buffer, "1/%.0f", 1.0 / d);
             else
-                sprintf (buffer, "%0.1f", d);
+                sprintf (buffer, "%.1f", d);
             return buffer;
         }
 };
@@ -307,7 +313,9 @@ class FocalLengthInterpreter : public Interpreter {
         FocalLengthInterpreter () {}
         virtual std::string toString (Tag* t) {
         	char buffer[32];
-            sprintf (buffer, "%0.1f", t->toDouble());
+        	double v = t->toDouble();
+        	if( v>1000000. || v<0 ) return "undef";
+            sprintf (buffer, "%.1f", v );
             return buffer;
         }
 };