diff --git a/src/riscv/riscv.c b/src/riscv/riscv.c
index a069916..6d7bf83 100644
--- a/src/riscv/riscv.c
+++ b/src/riscv/riscv.c
@@ -28,6 +28,27 @@ int64_t get_peak_performance(struct cpuInfo* cpu) {
   return flops;
 }
 
+// Returns the length of the multi-letter
+// extension, or -1 if an error occurs
+int parse_multi_letter_extension(struct extensions* ext, char* e) {
+  if(*e != '_') return -1;
+  char* multi_letter_extension_end = strstr(e+1, "_");
+  if(multi_letter_extension_end == NULL) {
+    // This is the last extension, find the end
+    // of the string
+    multi_letter_extension_end = e + strlen(e);
+  }
+
+  int multi_letter_extension_len = multi_letter_extension_end-(e+1);
+
+  // TODO: Parse extension and fill ext struct
+  char* multi_letter_extension = emalloc(multi_letter_extension_len);
+  strncpy(multi_letter_extension, e+1, multi_letter_extension_len);
+  printWarn("Not parsed multi-letter extension: %s", multi_letter_extension);
+
+  return multi_letter_extension_len;
+}
+
 struct extensions* get_extensions_from_str(char* str) {
   struct extensions* ext = emalloc(sizeof(struct extensions));
   ext->mask = 0;
@@ -42,7 +63,7 @@ struct extensions* get_extensions_from_str(char* str) {
   memset(ext->str, 0, len);
   strncpy(ext->str, str, sizeof(char) * len);
 
-  // Code inspired in Linux kernel:
+  // Code inspired in Linux kernel (riscv_fill_hwcap):
   // https://elixir.bootlin.com/linux/v6.2.10/source/arch/riscv/kernel/cpufeature.c
   char* isa = str;
   if (!strncmp(isa, "rv32", 4))
@@ -55,8 +76,18 @@ struct extensions* get_extensions_from_str(char* str) {
   }
 
   for(char* e = isa; *e != '\0'; e++) {
-    int n = *e - 'a';
-    ext->mask |= 1UL << n;
+    if(*e == '_') {
+      // Multi-letter extension
+      int multi_letter_extension_len = parse_multi_letter_extension(ext, e);
+      if(multi_letter_extension_len == -1) {
+        return ext;
+      }
+      e += multi_letter_extension_len;
+    }
+    else {
+      int n = *e - 'a';
+      ext->mask |= 1UL << n;
+    }
   }
 
   return ext;