diff --git a/src/common/commandoption.c b/src/common/commandoption.c
index e05cdbf92..d1824d0fc 100644
--- a/src/common/commandoption.c
+++ b/src/common/commandoption.c
@@ -11,7 +11,7 @@
 
 bool ffParseModuleOptions(const char* key, const char* value)
 {
-    if (!ffStrStartsWith(key, "--") || !isalpha(key[2])) return false;
+    if (!ffStrStartsWith(key, "--") || !ffCharIsEnglishAlphabet(key[2])) return false;
 
     for (FFModuleBaseInfo** modules = ffModuleInfos[toupper(key[2]) - 'A']; *modules; ++modules)
     {
@@ -102,7 +102,7 @@ static void parseStructureCommand(
         }
     }
 
-    if(isalpha(line[0]))
+    if(ffCharIsEnglishAlphabet(line[0]))
     {
         for (FFModuleBaseInfo** modules = ffModuleInfos[toupper(line[0]) - 'A']; *modules; ++modules)
         {
diff --git a/src/common/jsonconfig.c b/src/common/jsonconfig.c
index 3131cd750..de34b2b10 100644
--- a/src/common/jsonconfig.c
+++ b/src/common/jsonconfig.c
@@ -94,7 +94,7 @@ static inline void genJsonResult(FFModuleBaseInfo* baseInfo, yyjson_mut_doc* doc
 
 static bool parseModuleJsonObject(const char* type, yyjson_val* jsonVal, yyjson_mut_doc* jsonDoc)
 {
-    if(!isalpha(type[0])) return false;
+    if(!ffCharIsEnglishAlphabet(type[0])) return false;
 
     for (FFModuleBaseInfo** modules = ffModuleInfos[toupper(type[0]) - 'A']; *modules; ++modules)
     {
diff --git a/src/fastfetch.c b/src/fastfetch.c
index 629c4dad0..474abd78f 100644
--- a/src/fastfetch.c
+++ b/src/fastfetch.c
@@ -249,7 +249,7 @@ static void printCommandHelp(const char* command)
         puts(FASTFETCH_DATATEXT_HELP_COLOR);
     else if(ffStrEqualsIgnCase(command, "format"))
         puts(FASTFETCH_DATATEXT_HELP_FORMAT);
-    else if(isalpha(command[0]) && ffStrEndsWithIgnCase(command, "-format")) // <module>-format
+    else if(ffCharIsEnglishAlphabet(command[0]) && ffStrEndsWithIgnCase(command, "-format")) // <module>-format
         printCommandFormatHelp(command);
     else if(!printSpecificCommandHelp(command))
         fprintf(stderr, "Error: No specific help for command '%s' provided\n", command);
diff --git a/src/util/stringUtils.h b/src/util/stringUtils.h
index dd5d7e5ba..ad24057b5 100644
--- a/src/util/stringUtils.h
+++ b/src/util/stringUtils.h
@@ -69,3 +69,8 @@ static inline bool ffStrContainsC(const char* str, char compareTo)
 {
     return strchr(str, compareTo) != NULL;
 }
+
+static inline bool ffCharIsEnglishAlphabet(char c)
+{
+    return ('a' <= c && c <= 'z') || ('A' <= c && c <= 'Z');
+}