diff --git a/png.c b/png.c
index 1bcf042..9cc560e 100644
--- a/png.c
+++ b/png.c
@@ -53,7 +53,7 @@
 int PNGAPI
 png_sig_cmp(png_const_bytep sig, size_t start, size_t num_to_check)
 {
-   png_byte png_signature[8] = {137, 80, 78, 71, 13, 10, 26, 10};
+   static const png_byte png_signature[8] = {137, 80, 78, 71, 13, 10, 26, 10};
 
    if (num_to_check > 8)
       num_to_check = 8;
@@ -731,7 +731,7 @@
 
    {
       size_t pos = 0;
-      char number_buf[5]; /* enough for a four-digit year */
+      char number_buf[5] = {0, 0, 0, 0, 0}; /* enough for a four-digit year */
 
 #     define APPEND_STRING(string) pos = png_safecat(out, 29, pos, (string))
 #     define APPEND_NUMBER(format, value)\
@@ -3218,7 +3218,7 @@
       if (num <= 0x80000000) /* else overflowed */
       {
          unsigned int ndigits = 0, first = 16 /* flag value */;
-         char digits[10];
+         char digits[10] = {0};
 
          while (num)
          {
diff --git a/pngerror.c b/pngerror.c
index ec3a709..53e79ba 100644
--- a/pngerror.c
+++ b/pngerror.c
@@ -255,7 +255,7 @@
 png_warning_parameter_unsigned(png_warning_parameters p, int number, int format,
     png_alloc_size_t value)
 {
-   char buffer[PNG_NUMBER_BUFFER_SIZE];
+   char buffer[PNG_NUMBER_BUFFER_SIZE] = {0};
    png_warning_parameter(p, number, PNG_FORMAT_NUMBER(buffer, format, value));
 }
 
@@ -265,7 +265,7 @@
 {
    png_alloc_size_t u;
    png_charp str;
-   char buffer[PNG_NUMBER_BUFFER_SIZE];
+   char buffer[PNG_NUMBER_BUFFER_SIZE] = {0};
 
    /* Avoid overflow by doing the negate in a png_alloc_size_t: */
    u = (png_alloc_size_t)value;