diff --git a/tools/ld-chroma-decoder/yiq.cpp b/tools/ld-chroma-decoder/yiq.cpp
index f52eacca4..4bfcc5afd 100644
--- a/tools/ld-chroma-decoder/yiq.cpp
+++ b/tools/ld-chroma-decoder/yiq.cpp
@@ -30,7 +30,7 @@ YIQ::YIQ(qreal _y, qreal _i, qreal _q)
 {
 }
 
-YIQ YIQ::operator*=(qreal x)
+YIQ YIQ::operator*=(qreal x) const
 {
     YIQ o;
 
@@ -41,7 +41,7 @@ YIQ YIQ::operator*=(qreal x)
     return o;
 }
 
-YIQ YIQ::operator+=(const YIQ &p)
+YIQ YIQ::operator+=(const YIQ &p) const
 {
     YIQ o;
 
diff --git a/tools/ld-chroma-decoder/yiq.h b/tools/ld-chroma-decoder/yiq.h
index 62d909635..740003b90 100644
--- a/tools/ld-chroma-decoder/yiq.h
+++ b/tools/ld-chroma-decoder/yiq.h
@@ -34,8 +34,8 @@ class YIQ
     qreal y, i, q;
 
     YIQ(qreal y = 0.0, qreal i = 0.0, qreal q = 0.0);
-    YIQ operator*=(qreal x);
-    YIQ operator+=(const YIQ &p);
+    YIQ operator*=(qreal x) const;
+    YIQ operator+=(const YIQ &p) const;
 
 private:
 
diff --git a/tools/ld-discmap/frame.cpp b/tools/ld-discmap/frame.cpp
index 959856299..2ee506f69 100644
--- a/tools/ld-discmap/frame.cpp
+++ b/tools/ld-discmap/frame.cpp
@@ -168,7 +168,7 @@ void Frame::secondField(qint32 value)
 }
 
 // Overide less than operator for sorting
-bool Frame::operator<(const Frame& other)
+bool Frame::operator<(const Frame& other) const
 {
     return (m_vbiFrameNumber < other.m_vbiFrameNumber) ||
             ((m_vbiFrameNumber == other.m_vbiFrameNumber) && (other.m_isPullDown));
diff --git a/tools/ld-discmap/frame.h b/tools/ld-discmap/frame.h
index 9356fce04..c3f68e535 100644
--- a/tools/ld-discmap/frame.h
+++ b/tools/ld-discmap/frame.h
@@ -37,7 +37,7 @@ class Frame
           const qint32 &firstField = -1, const qint32 &secondField = -1);
     ~Frame() = default;
     Frame(const Frame &) = default;
-    Frame &operator =(const Frame &) = default;
+    Frame &operator=(const Frame &) = default;
 
     // Get
     qint32 seqFrameNumber() const;
@@ -66,7 +66,7 @@ class Frame
     void secondField(qint32 value);
 
     // Operators
-    bool operator <(const Frame &);
+    bool operator<(const Frame &) const;
 
 private:
     qint32 m_seqFrameNumber;