diff --git a/src/base/convert_to.h b/src/base/convert_to.h
index 83d036043..89d4a85db 100644
--- a/src/base/convert_to.h
+++ b/src/base/convert_to.h
@@ -18,11 +18,7 @@ namespace base {
   // Undefined convertion
   template<typename To, typename From>
   To convert_to(const From& from) {
-    // As this function doesn't return a value, if a specialization is
-    // not found, a compiler error will be thrown (which means that
-    // the conversion isn't supported).
-
-    // TODO Use a static_assert(false)
+    static_assert(false && sizeof(To), "Invalid conversion");
   }
 
   template<> int convert_to(const std::string& from);
diff --git a/src/raster/algofill.cpp b/src/raster/algofill.cpp
index 051276200..9fbc4d75f 100644
--- a/src/raster/algofill.cpp
+++ b/src/raster/algofill.cpp
@@ -93,23 +93,23 @@ static inline bool color_equal_8(color_t c1, color_t c2, int tolerance)
 template<typename ImageTraits>
 static inline bool color_equal(color_t c1, color_t c2, int tolerance)
 {
-  // TODO static_assert(false)
+  static_assert(false && sizeof(ImageTraits), "Invalid color comparison");
 }
 
 template<>
-static inline bool color_equal<RgbTraits>(color_t c1, color_t c2, int tolerance)
+inline bool color_equal<RgbTraits>(color_t c1, color_t c2, int tolerance)
 {
   return color_equal_32(c1, c2, tolerance);
 }
 
 template<>
-static inline bool color_equal<GrayscaleTraits>(color_t c1, color_t c2, int tolerance)
+inline bool color_equal<GrayscaleTraits>(color_t c1, color_t c2, int tolerance)
 {
   return color_equal_16(c1, c2, tolerance);
 }
 
 template<>
-static inline bool color_equal<IndexedTraits>(color_t c1, color_t c2, int tolerance)
+inline bool color_equal<IndexedTraits>(color_t c1, color_t c2, int tolerance)
 {
   return color_equal_8(c1, c2, tolerance);
 }
diff --git a/src/raster/conversion_alleg.cpp b/src/raster/conversion_alleg.cpp
index 2c1b411d0..83785f219 100644
--- a/src/raster/conversion_alleg.cpp
+++ b/src/raster/conversion_alleg.cpp
@@ -38,9 +38,7 @@ namespace {
 
 template<typename ImageTraits, int color_depth>
 int convert_color_to_allegro(color_t color, const Palette* palette) {
-  // Error, it must use a specialization
-
-  // TODO Use a static_assert(false)
+  static_assert(false && sizeof(ImageTraits), "Invalid color conversion");
 }
 
 template<>
diff --git a/src/raster/conversion_she.cpp b/src/raster/conversion_she.cpp
index ce5c5abab..634292524 100644
--- a/src/raster/conversion_she.cpp
+++ b/src/raster/conversion_she.cpp
@@ -41,9 +41,7 @@ namespace {
 
 template<typename ImageTraits, she::SurfaceFormat format>
 uint32_t convert_color_to_surface(color_t color, const Palette* palette, const she::SurfaceFormatData* fd) {
-  // Error, it must use a specialization
-
-  // TODO Use a static_assert(false)
+  static_assert(false && sizeof(ImageTraits), "Invalid color conversion");
 }
 
 template<>