diff --git a/yjit/src/backend/arm64/mod.rs b/yjit/src/backend/arm64/mod.rs
index a74e5cf0ff..01485d1df6 100644
--- a/yjit/src/backend/arm64/mod.rs
+++ b/yjit/src/backend/arm64/mod.rs
@@ -1085,6 +1085,9 @@ impl Assembler
                 Insn::Jbe(target) => {
                     emit_conditional_jump::<{Condition::LS}>(cb, compile_side_exit(*target, self, ocb));
                 },
+                Insn::Jb(target) => {
+                    emit_conditional_jump::<{Condition::CC}>(cb, compile_side_exit(*target, self, ocb));
+                },
                 Insn::Jo(target) => {
                     emit_conditional_jump::<{Condition::VS}>(cb, compile_side_exit(*target, self, ocb));
                 },
diff --git a/yjit/src/backend/ir.rs b/yjit/src/backend/ir.rs
index 4e7e9a1542..888922579d 100644
--- a/yjit/src/backend/ir.rs
+++ b/yjit/src/backend/ir.rs
@@ -423,9 +423,12 @@ pub enum Insn {
     // Produces no output
     IncrCounter { mem: Opnd, value: Opnd },
 
-    /// Jump if below or equal
+    /// Jump if below or equal (unsigned)
     Jbe(Target),
 
+    /// Jump if below (unsigned)
+    Jb(Target),
+
     /// Jump if equal
     Je(Target),
 
@@ -579,6 +582,7 @@ impl Insn {
             Insn::FrameTeardown => "FrameTeardown",
             Insn::IncrCounter { .. } => "IncrCounter",
             Insn::Jbe(_) => "Jbe",
+            Insn::Jb(_) => "Jb",
             Insn::Je(_) => "Je",
             Insn::Jl(_) => "Jl",
             Insn::Jg(_) => "Jg",
@@ -727,6 +731,7 @@ impl<'a> Iterator for InsnOpndIterator<'a> {
             Insn::FrameSetup |
             Insn::FrameTeardown |
             Insn::Jbe(_) |
+            Insn::Jb(_) |
             Insn::Je(_) |
             Insn::Jl(_) |
             Insn::Jg(_) |
@@ -825,6 +830,7 @@ impl<'a> InsnOpndMutIterator<'a> {
             Insn::FrameSetup |
             Insn::FrameTeardown |
             Insn::Jbe(_) |
+            Insn::Jb(_) |
             Insn::Je(_) |
             Insn::Jl(_) |
             Insn::Jg(_) |
diff --git a/yjit/src/backend/x86_64/mod.rs b/yjit/src/backend/x86_64/mod.rs
index 1ae5ee7477..f60a31a9c3 100644
--- a/yjit/src/backend/x86_64/mod.rs
+++ b/yjit/src/backend/x86_64/mod.rs
@@ -709,6 +709,14 @@ impl Assembler
                     }
                 },
 
+                Insn::Jb(target) => {
+                    match compile_side_exit(*target, self, ocb) {
+                        Target::CodePtr(code_ptr) | Target::SideExitPtr(code_ptr) => jb_ptr(cb, code_ptr),
+                        Target::Label(label_idx) => jb_label(cb, label_idx),
+                        Target::SideExit { .. } => unreachable!("Target::SideExit should have been compiled by compile_side_exit"),
+                    }
+                },
+
                 Insn::Jz(target) => {
                     match compile_side_exit(*target, self, ocb) {
                         Target::CodePtr(code_ptr) | Target::SideExitPtr(code_ptr) => jz_ptr(cb, code_ptr),