diff --git a/CHANGES.md b/CHANGES.md
index ac9b37a..4ce126b 100644
--- a/CHANGES.md
+++ b/CHANGES.md
@@ -14,6 +14,7 @@ v1.4.0 - YYYY-MM-DD
   with `pdfioFileCreateFontObjFromBase` (Issue #84)
 - Fixed reading of PDF files whose trailer is missing a newline (Issue #80)
 - Fixed builds with some versions of VC++ (Issue #81)
+- Fixed validation of date/time values (Issue #83)
 
 
 v1.3.2 - 2024-08-15
diff --git a/pdfio-value.c b/pdfio-value.c
index 9fe960f..8bf95b9 100644
--- a/pdfio-value.c
+++ b/pdfio-value.c
@@ -755,6 +755,8 @@ get_date_time(const char *s)		// I - PDF date/time value
   int		offset;			// Date offset
 
 
+  PDFIO_DEBUG("get_date_time(s=\"%s\")\n", s);
+
   // Possible date value of the form:
   //
   //   (D:YYYYMMDDhhmmssZ)
@@ -772,10 +774,12 @@ get_date_time(const char *s)		// I - PDF date/time value
   {
     if (s[i] == 'Z')
     {
+      // UTC...
       i ++;
     }
     else if (s[i] == '-' || s[i] == '+')
     {
+      // Timezone offset from UTC...
       if (isdigit(s[i + 1] & 255) && isdigit(s[i + 2] & 255) && s[i + 3] == '\'' && isdigit(s[i + 4] & 255) && isdigit(s[i + 5] & 255))
       {
 	i += 6;
@@ -783,6 +787,11 @@ get_date_time(const char *s)		// I - PDF date/time value
 	  i ++;
       }
     }
+    else if (!s[i])
+    {
+      // Missing zone info, invalid date string...
+      return (0);
+    }
   }
 
   if (s[i])