diff --git a/vendor/patches/riscv/riscv-isa-sim/0007-SPIKE-Fix-decoder-cvxif.patch b/vendor/patches/riscv/riscv-isa-sim/0007-SPIKE-Fix-decoder-cvxif.patch
new file mode 100644
index 0000000000..230c11450b
--- /dev/null
+++ b/vendor/patches/riscv/riscv-isa-sim/0007-SPIKE-Fix-decoder-cvxif.patch
@@ -0,0 +1,13 @@
+diff --git a/vendor/riscv/riscv-isa-sim/customext/cvxif.cc b/vendor/riscv/riscv-isa-sim/customext/cvxif.cc
+index b1bef8e6..20aea89c 100644
+--- a/vendor/riscv/riscv-isa-sim/customext/cvxif.cc
++++ b/vendor/riscv/riscv-isa-sim/customext/cvxif.cc
+@@ -101,7 +101,7 @@ class cvxif_t : public cvxif_extn_t
+       case FUNC3_0:
+         switch (r_insn.funct7 & 0x1) {
+           case NO_RS3:
+-            switch (r_insn.funct7 & 0xe) {
++            switch (r_insn.funct7 & 0x7e) {
+               case CUS_NOP:
+                 break;
+               case CUS_U_ADD:
diff --git a/vendor/riscv/riscv-isa-sim/customext/cvxif.cc b/vendor/riscv/riscv-isa-sim/customext/cvxif.cc
index b1bef8e646..20aea89cb4 100644
--- a/vendor/riscv/riscv-isa-sim/customext/cvxif.cc
+++ b/vendor/riscv/riscv-isa-sim/customext/cvxif.cc
@@ -101,7 +101,7 @@ class cvxif_t : public cvxif_extn_t
       case FUNC3_0:
         switch (r_insn.funct7 & 0x1) {
           case NO_RS3:
-            switch (r_insn.funct7 & 0xe) {
+            switch (r_insn.funct7 & 0x7e) {
               case CUS_NOP:
                 break;
               case CUS_U_ADD: