diff --git a/CHANGELOG.md b/CHANGELOG.md
index 1985e92d..43b8f941 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -7,6 +7,7 @@ HEAD
 * Removed dependency on `PGM_P` as Particle 0.6.2 doesn't define it (issue #546)
 * Fixed warning "dereferencing type-punned pointer will break strict-aliasing rules [-Wstrict-aliasing]"
 * Fixed warning "floating constant exceeds range of 'float' [-Woverflow]" (issue #544)
+* Fixed warning "this statement may fall through" [-Wimplicit-fallthrough=] (issue #539)
 * Removed `ARDUINOJSON_DOUBLE_IS_64BITS` as it became useless.
 * Fixed too many decimals places in float serialization (issue #543)
 
diff --git a/src/ArduinoJson/Polyfills/parseFloat.hpp b/src/ArduinoJson/Polyfills/parseFloat.hpp
index d3ed2397..e5d99f1b 100644
--- a/src/ArduinoJson/Polyfills/parseFloat.hpp
+++ b/src/ArduinoJson/Polyfills/parseFloat.hpp
@@ -26,8 +26,11 @@ inline T parseFloat(const char* s) {
   switch (*s) {
     case '-':
       negative_result = true;
+      s++;
+      break;
     case '+':
       s++;
+      break;
   }
 
   if (*s == 't') return 1;  // true
diff --git a/src/ArduinoJson/Polyfills/parseInteger.hpp b/src/ArduinoJson/Polyfills/parseInteger.hpp
index 7d353fb4..023d7bcb 100644
--- a/src/ArduinoJson/Polyfills/parseInteger.hpp
+++ b/src/ArduinoJson/Polyfills/parseInteger.hpp
@@ -26,6 +26,8 @@ T parseInteger(const char *s) {
   switch (*s) {
     case '-':
       negative_result = true;
+      s++;
+      break;
     case '+':
       s++;
       break;