diff --git a/src/util/string_buffer.h b/src/util/string_buffer.h
index db49d4d82..6b94e3686 100644
--- a/src/util/string_buffer.h
+++ b/src/util/string_buffer.h
@@ -43,6 +43,7 @@ class string_buffer {
         m_capacity = new_capacity;
         m_buffer   = new_buffer;
     }
+
     static const unsigned c_buffer_size = 24;
 
 public:  
@@ -82,28 +83,20 @@ public:
 
     void append(int n) {
         char buffer[c_buffer_size]; 
-#ifdef _WINDOWS
-        sprintf_s(buffer, c_buffer_size, "%d", n);
-#else
-        sprintf(buffer, "%d", n);
-#endif 
+        SPRINTF_D(buffer, n);
         append(buffer);
     }
 
     void append(unsigned n) {
         char buffer[c_buffer_size]; 
-#ifdef _WINDOWS
-        sprintf_s(buffer, c_buffer_size, "%d", n);
-#else
-        sprintf(buffer, "%d", n);
-#endif
+        SPRINTF_U(buffer, n);
         append(buffer);
     }
 
     void append(long n) {
         char buffer[c_buffer_size]; 
 #ifdef _WINDOWS
-        sprintf_s(buffer, c_buffer_size, "%ld", n);
+        sprintf_s(buffer, Z3_ARRAYSIZE(buffer), "%ld", n);
 #else
         sprintf(buffer, "%ld", n);
 #endif
diff --git a/src/util/util.h b/src/util/util.h
index 4ccf76289..b9f3bdc28 100644
--- a/src/util/util.h
+++ b/src/util/util.h
@@ -48,13 +48,13 @@ static_assert(sizeof(int64_t) == 8, "64 bits");
 
 #ifdef _WINDOWS
 #define SSCANF sscanf_s
-#define SPRINTF sprintf_s
+// #define SPRINTF sprintf_s
 #define SPRINTF_D(_buffer_, _i_) sprintf_s(_buffer_, Z3_ARRAYSIZE(_buffer_), "%d", _i_)
 #define SPRINTF_U(_buffer_, _u_) sprintf_s(_buffer_, Z3_ARRAYSIZE(_buffer_), "%u", _u_)
 #define _Exit exit
 #else
 #define SSCANF sscanf
-#define SPRINTF sprintf
+// #define SPRINTF sprintf
 #define SPRINTF_D(_buffer_, _i_) sprintf(_buffer_, "%d", _i_)
 #define SPRINTF_U(_buffer_, _u_) sprintf(_buffer_, "%u", _u_)
 #endif