diff --git a/common/lib_id.cpp b/common/lib_id.cpp
index 388f0cbe93..f92d3ce314 100644
--- a/common/lib_id.cpp
+++ b/common/lib_id.cpp
@@ -403,18 +403,19 @@ const unsigned schIllegalChars[] = { BASE_ILLEGAL_CHARS, ' ' };
 const unsigned pcbIllegalChars[] = { BASE_ILLEGAL_CHARS, 0 };
 #define ILL_CHAR_SIZE (sizeof(schIllegalChars) / sizeof(int))
 
-bool LIB_ID::isLegalChar( unsigned aChar, LIB_ID_TYPE aType )
+bool LIB_ID::isLegalChar( unsigned aUniChar, LIB_ID_TYPE aType )
 {
     const unsigned (&illegalChars)[ILL_CHAR_SIZE] =
         aType == ID_SCH ? schIllegalChars : pcbIllegalChars;
 
     for( const unsigned ch : illegalChars )
     {
-        if( ch == aChar )
+        if( ch == aUniChar )
             return false;
     }
 
-    if( !wxIsascii( aChar ) )
+    // Test for "printable" code (aUniChar is a unicode (32 bits) char, not a ASCII value )
+    if( aUniChar < ' ' )
         return false;
 
     return true;
diff --git a/eeschema/project_rescue.cpp b/eeschema/project_rescue.cpp
index 5bf514a734..a451605f7b 100644
--- a/eeschema/project_rescue.cpp
+++ b/eeschema/project_rescue.cpp
@@ -137,7 +137,6 @@ void RESCUE_CASE_CANDIDATE::FindRescues( RESCUER& aRescuer,
 {
     typedef std::map<wxString, RESCUE_CASE_CANDIDATE> candidate_map_t;
     candidate_map_t candidate_map;
-
     // Remember the list of components is sorted by part name.
     // So a search in libraries is made only once by group
     LIB_ALIAS* case_sensitive_match = nullptr;
@@ -380,15 +379,17 @@ void RESCUE_SYMBOL_LIB_TABLE_CANDIDATE::FindRescues(
 
             // Test whether there is a conflict or if the symbol can only be found in the cache.
             if( ( ( cache_match && lib_match
-                  && !cache_match->PinsConflictWith( *lib_match, true, true, true, true, false ) )
-                || (!cache_match && lib_match ) )
-              && !LIB_ID::HasIllegalChars( part_id.GetLibItemName(), LIB_ID::ID_SCH ) )
+                    && !cache_match->PinsConflictWith( *lib_match, true, true, true, true, false ) )
+                  || (!cache_match && lib_match ) )
+                && !LIB_ID::HasIllegalChars( part_id.GetLibItemName(), LIB_ID::ID_SCH ) )
+            {
                 continue;
+            }
 
             // Fix illegal LIB_ID name characters.
             wxString new_name = LIB_ID::FixIllegalChars( part_id.GetLibItemName(), LIB_ID::ID_SCH );
 
-            // Differentiate symbol name in the resue library by appending the symbol library
+            // Differentiate symbol name in the rescue library by appending the symbol library
             // table nickname to the symbol name to prevent name clashes in the rescue library.
             wxString libNickname = GetRescueLibraryFileName().GetName();
 
diff --git a/include/lib_id.h b/include/lib_id.h
index f4c2277f62..3b17789e13 100644
--- a/include/lib_id.h
+++ b/include/lib_id.h
@@ -236,8 +236,11 @@ public:
 #endif
 
 protected:
-    ///> Tests whether a character is a legal LIB_ID character
-    static bool isLegalChar( unsigned aChar, LIB_ID_TYPE aType );
+    /** Tests whether a unicode character is a legal LIB_ID character
+     * note: aUniChar is expected to be a unicode 32 bits char, not a UTF8 char, that use
+     * a variable lenght coding value
+     */
+    static bool isLegalChar( unsigned aUniChar, LIB_ID_TYPE aType );
 
     UTF8    nickname;       ///< The nickname of the library or empty.
     UTF8    item_name;      ///< The name of the entry in the logical library.