diff --git a/ql-iob-plugin/pcf_parser.cc b/ql-iob-plugin/pcf_parser.cc
index ea93762..c7a9309 100644
--- a/ql-iob-plugin/pcf_parser.cc
+++ b/ql-iob-plugin/pcf_parser.cc
@@ -19,7 +19,6 @@
  */
 #include "pcf_parser.hh"
 
-#include <fstream>
 #include <regex>
 
 // ============================================================================
@@ -27,11 +26,10 @@
 bool PcfParser::parse (const std::string& a_FileName) {
 
     // Open the file
-    std::fstream file(a_FileName.c_str(), std::ifstream::in);
+    std::ifstream file(a_FileName.c_str());
 
     // Parse it
-    std::istream* stream = &file;
-    return parse(stream);
+    return parse(file);
 }
 
 const std::vector<PcfParser::Constraint> PcfParser::getConstraints () const {
@@ -41,9 +39,9 @@
 
 // ============================================================================
 
-bool PcfParser::parse (std::istream*& a_Stream) {
+bool PcfParser::parse (std::ifstream& a_Stream) {
 
-    if (a_Stream == nullptr) {
+    if (!a_Stream.good()) {
         return false;
     }
 
@@ -53,9 +51,9 @@
     // Parse PCF lines
     std::regex re("^\\s*set_io\\s+([^#\\s]+)\\s+([^#\\s]+)(?:\\s+#(.*))?");
 
-    while (a_Stream->good()) {
+    while (a_Stream.good()) {
         std::string line;
-        std::getline(*a_Stream, line);
+        std::getline(a_Stream, line);
 
         // Match against regex
         std::cmatch cm;
diff --git a/ql-iob-plugin/pcf_parser.hh b/ql-iob-plugin/pcf_parser.hh
index 22263fd..8a4a920 100644
--- a/ql-iob-plugin/pcf_parser.hh
+++ b/ql-iob-plugin/pcf_parser.hh
@@ -20,7 +20,7 @@
 #ifndef PCF_PARSER_HH
 #define PCF_PARSER_HH
 
-#include <istream>
+#include <fstream>
 #include <string>
 #include <vector>
 
@@ -51,12 +51,12 @@
     /// Parses a PCF file and stores constraint within the class instance.
     /// Returns false in case of error
     bool parse (const std::string& a_FileName);
-    bool parse (std::istream*& a_Stream);
+    bool parse (std::ifstream& a_Stream);
 
     /// Returns the constraint list
     const std::vector<Constraint> getConstraints () const;
 
-protected:
+private:
 
     /// A list of constraints
     std::vector<Constraint> m_Constraints;
diff --git a/ql-iob-plugin/pinmap_parser.cc b/ql-iob-plugin/pinmap_parser.cc
index 89a8da8..77e3662 100644
--- a/ql-iob-plugin/pinmap_parser.cc
+++ b/ql-iob-plugin/pinmap_parser.cc
@@ -19,7 +19,6 @@
  */
 #include "pinmap_parser.hh"
 
-#include <fstream>
 #include <sstream>
 
 // ============================================================================
@@ -27,11 +26,10 @@
 bool PinmapParser::parse (const std::string& a_FileName) {
 
     // Open the file
-    std::fstream file(a_FileName.c_str(), std::ifstream::in);
+    std::ifstream file(a_FileName.c_str());
 
     // Parse it
-    std::istream* stream = &file;
-    return parse(stream);
+    return parse(file);
 }
 
 const std::vector<PinmapParser::Entry> PinmapParser::getEntries() const {
@@ -55,23 +53,27 @@
     return fields;
 }
 
-bool PinmapParser::parseHeader (std::istream*& a_Stream) {
+bool PinmapParser::parseHeader (std::ifstream& a_Stream) {
 
     // Get the header line
     std::string header;
-    std::getline(*a_Stream, header);
+    std::getline(a_Stream, header);
 
     // Parse fields
     m_Fields = getFields(header);
+    if (m_Fields.empty()) {
+        return false;
+    }
+
     return true;
 }
 
-bool PinmapParser::parseData (std::istream*& a_Stream) {
+bool PinmapParser::parseData (std::ifstream& a_Stream) {
 
     // Parse lines as they come
-    while (a_Stream->good()) {
+    while (a_Stream.good()) {
         std::string line;
-        std::getline(*a_Stream, line);
+        std::getline(a_Stream, line);
 
         if (line.empty()) {
             continue;
@@ -83,6 +85,11 @@
         // Assign data fields to columns
         Entry entry;
         for (size_t i=0; i<data.size(); ++i) {
+
+            if (i >= m_Fields.size()) {
+                return false;
+            }
+
             entry[m_Fields[i]] = data[i];
         }
 
@@ -92,9 +99,9 @@
     return true;
 }
 
-bool PinmapParser::parse (std::istream*& a_Stream) {
+bool PinmapParser::parse (std::ifstream& a_Stream) {
 
-    if (a_Stream == nullptr) {
+    if (!a_Stream.good()) {
         return false;
     }
 
diff --git a/ql-iob-plugin/pinmap_parser.hh b/ql-iob-plugin/pinmap_parser.hh
index 6d729be..5139244 100644
--- a/ql-iob-plugin/pinmap_parser.hh
+++ b/ql-iob-plugin/pinmap_parser.hh
@@ -20,7 +20,7 @@
 #ifndef PINMAP_PARSER_HH
 #define PINMAP_PARSER_HH
 
-#include <istream>
+#include <fstream>
 #include <string>
 #include <vector>
 #include <map>
@@ -38,21 +38,21 @@
 
     /// Parses a pinmap CSV file
     bool parse (const std::string& a_FileName);
-    bool parse (std::istream*& a_Stream);
+    bool parse (std::ifstream& a_Stream);
 
     /// Returns a vector of entries
     const std::vector<Entry> getEntries() const;
 
-protected:
+private:
 
     /// Splits the input string into a vector of fields. Fields are comma
     /// separated.
     static std::vector<std::string> getFields (const std::string& a_String);
 
     /// Parses the header
-    bool parseHeader (std::istream*& a_Stream);
+    bool parseHeader (std::ifstream& a_Stream);
     /// Parses the data
-    bool parseData   (std::istream*& a_Stream);
+    bool parseData   (std::ifstream& a_Stream);
 
     /// Header fields
     std::vector<std::string> m_Fields;