diff --git a/cpu/ppc/ppcdisasm.cpp b/cpu/ppc/ppcdisasm.cpp
index 8205333861..059e6e3199 100644
--- a/cpu/ppc/ppcdisasm.cpp
+++ b/cpu/ppc/ppcdisasm.cpp
@@ -1176,14 +1176,14 @@ void opc_group31(PPCDisasmContext* ctx) {
             if (!rs && !ra)
                 opc_illegal(ctx);
             else {
-                ctx->instr_str = my_sprintf("%-7s r%s", "tlbld", rb);
+                ctx->instr_str = my_sprintf("%-7s r%d", "tlbld", rb);
                 add_reg_in(ctx, "r%d", rb);
             }
-        } else if (index == 30) { /* tlbli - 603 only */
+        } else if (index == 31) { /* tlbli - 603 only */
             if (!rs && !ra)
                 opc_illegal(ctx);
             else {
-                ctx->instr_str = my_sprintf("%-7s r%s", "tlbli", rb);
+                ctx->instr_str = my_sprintf("%-7s r%d", "tlbli", rb);
                 add_reg_in(ctx, "r%d", rb);
             }
         }
@@ -1250,10 +1250,10 @@ void opc_group31(PPCDisasmContext* ctx) {
                 add_reg_out(ctx, "cr");
             }
         } else {
-            strcpy(opcode, opc_logic[index]);
-            if (!strlen(opcode)) {
+            if (index >= 16 || !strlen(opc_logic[index])) {
                 opc_illegal(ctx);
             } else {
+                strcpy(opcode, opc_logic[index]);
                 if (rc_set) {
                     strcat(opcode, ".");
                     add_reg_out(ctx, "cr");
diff --git a/cpu/ppc/test/ppcdisasmtest.csv b/cpu/ppc/test/ppcdisasmtest.csv
index e4706881e5..986285a59b 100644
--- a/cpu/ppc/test/ppcdisasmtest.csv
+++ b/cpu/ppc/test/ppcdisasmtest.csv
@@ -407,6 +407,10 @@
 0xFFF00100,0x7D453D2A,stswx,r10,r5,r7
 0xFFF00100,0x7C0002E4,tlbia
 0xFFF00100,0x7C004A64,tlbie,r9
+0xFFF00100,0x7C202FA4,tlbld,r5
+0xFFF00100,0x7C6007A4,tlbld,r0
+0xFFF00100,0x7C203FE4,tlbli,r7
+0xFFF00100,0x7C40FFE4,tlbli,r31
 
 # various simplified (extended) mnemonics
 0xFFF00100,0x60000000,nop