diff --git a/arch/riscv/kernel/cpufeature.c b/arch/riscv/kernel/cpufeature.c
index 7dd4589e79a4b..84dc44a3e6e5c 100644
--- a/arch/riscv/kernel/cpufeature.c
+++ b/arch/riscv/kernel/cpufeature.c
@@ -157,7 +157,7 @@ void __init riscv_fill_hwcap(void)
 		isa += 4;
 
 		bitmap_zero(this_isa, RISCV_ISA_EXT_MAX);
-		for (; *isa; ++isa) {
+		while (*isa) {
 			const char *ext = isa++;
 			const char *ext_end = isa;
 			bool ext_long = false, ext_err = false;
@@ -270,14 +270,12 @@ void __init riscv_fill_hwcap(void)
 
 			/*
 			 * The parser expects that at the start of an iteration isa points to the
-			 * character before the start of the next extension. This will not be the
-			 * case if we have just parsed a single-letter extension and the next
-			 * extension is not a multi-letter extension prefixed with an "_". It is
-			 * also not the case at the end of the string, where it will point to the
-			 * terminating null character.
+			 * first character of the next extension. As we stop parsing an extension
+			 * on meeting a non-alphanumeric character, an extra increment is needed
+			 * where the succeeding extension is a multi-letter prefixed with an "_".
 			 */
-			if (*isa != '_')
-				--isa;
+			if (*isa == '_')
+				++isa;
 
 #define SET_ISA_EXT_MAP(name, bit)							\
 			do {								\