diff --git a/ql/src/codeql_ruby/ast/internal/AST.qll b/ql/src/codeql_ruby/ast/internal/AST.qll
index 37ef071d507..0748deaad55 100644
--- a/ql/src/codeql_ruby/ast/internal/AST.qll
+++ b/ql/src/codeql_ruby/ast/internal/AST.qll
@@ -94,10 +94,10 @@ private module Cached {
       not strictcount(int i | exists(g.getParent().(Generated::LeftAssignmentList).getChild(i))) = 1
     } or
     TDivExpr(Generated::Binary g) { g instanceof @binary_slash } or
-    TDo(Generated::Do g) or
+    TDo(Generated::Do g) { exists(g.getChild(_)) } or
     TDoBlock(Generated::DoBlock g) { not g.getParent() instanceof Generated::Lambda } or
     TElementReference(Generated::ElementReference g) or
-    TElse(Generated::Else g) or
+    TElse(Generated::Else g) { exists(g.getChild(_)) } or
     TElsif(Generated::Elsif g) or
     TEmptyStmt(Generated::EmptyStatement g) or
     TEndBlock(Generated::EndBlock g) or
@@ -198,7 +198,7 @@ private module Cached {
     TSubshellLiteral(Generated::Subshell g) or
     TSymbolArrayLiteral(Generated::SymbolArray g) or
     TTernaryIfExpr(Generated::Conditional g) or
-    TThen(Generated::Then g) or
+    TThen(Generated::Then g) { exists(g.getChild(_)) } or
     TTokenConstantAccess(Generated::Constant g) {
       // A tree-sitter `constant` token is a read of that constant in any context
       // where an identifier would be a vcall.
diff --git a/ql/src/codeql_ruby/controlflow/internal/ControlFlowGraphImpl.qll b/ql/src/codeql_ruby/controlflow/internal/ControlFlowGraphImpl.qll
index f6c5367d8ec..49affd6b7a6 100644
--- a/ql/src/codeql_ruby/controlflow/internal/ControlFlowGraphImpl.qll
+++ b/ql/src/codeql_ruby/controlflow/internal/ControlFlowGraphImpl.qll
@@ -643,10 +643,17 @@ module Trees {
 
     final override predicate first(AstNode first) { first(this.getCondition(), first) }
 
+    private AstNode getConditionSucc() {
+      result = this.getBody()
+      or
+      not exists(this.getBody()) and
+      result = this.getCondition()
+    }
+
     final override predicate succ(AstNode pred, AstNode succ, Completion c) {
       last(this.getCondition(), pred, c) and
       this.entersLoopWhenConditionIs(c.(BooleanCompletion).getValue()) and
-      first(this.getBody(), succ)
+      first(this.getConditionSucc(), succ)
       or
       last(this.getBody(), pred, c) and
       first(this.getCondition(), succ) and
diff --git a/ql/test/library-tests/ast/Ast.expected b/ql/test/library-tests/ast/Ast.expected
index 8b74d275522..e5d03ac8d5b 100644
--- a/ql/test/library-tests/ast/Ast.expected
+++ b/ql/test/library-tests/ast/Ast.expected
@@ -671,6 +671,18 @@ control/conditionals.rb:
 #   58|       getBranch/getElse: [SubExpr] ... - ...
 #   58|         getAnOperand/getLeftOperand: [LocalVariableAccess] e
 #   58|         getAnOperand/getRightOperand: [IntegerLiteral] 2
+#   61|   getStmt: [IfExpr] if ...
+#   61|     getCondition: [GTExpr] ... > ...
+#   61|       getAnOperand/getGreaterOperand/getLeftOperand: [LocalVariableAccess] a
+#   61|       getAnOperand/getLesserOperand/getRightOperand: [LocalVariableAccess] b
+#   61|     getBranch/getThen: [StmtSequence] c
+#   62|       getStmt: [LocalVariableAccess] c
+#   67|   getStmt: [IfExpr] if ...
+#   67|     getCondition: [GTExpr] ... > ...
+#   67|       getAnOperand/getGreaterOperand/getLeftOperand: [LocalVariableAccess] a
+#   67|       getAnOperand/getLesserOperand/getRightOperand: [LocalVariableAccess] b
+#   68|     getBranch/getElse: [StmtSequence] c
+#   69|       getStmt: [LocalVariableAccess] c
 constants/constants.rb:
 #    1| [Toplevel] constants.rb
 #    1|   getStmt: [Module] ModuleA
@@ -1262,6 +1274,10 @@ control/loops.rb:
 #   63|     getCondition: [EqExpr] ... == ...
 #   63|       getAnOperand/getLeftOperand: [LocalVariableAccess] x
 #   63|       getAnOperand/getRightOperand: [IntegerLiteral] 0
+#   66|   getStmt: [WhileExpr] while ...
+#   66|     getCondition: [LTExpr] ... < ...
+#   66|       getAnOperand/getLeftOperand/getLesserOperand: [LocalVariableAccess] x
+#   66|       getAnOperand/getGreaterOperand/getRightOperand: [LocalVariableAccess] y
 misc/misc.rb:
 #    1| [Toplevel] misc.rb
 #    1|   getStmt: [AssignExpr] ... = ...
diff --git a/ql/test/library-tests/ast/control/ConditionalExpr.expected b/ql/test/library-tests/ast/control/ConditionalExpr.expected
index ce3c57f3471..ac2ac5ca057 100644
--- a/ql/test/library-tests/ast/control/ConditionalExpr.expected
+++ b/ql/test/library-tests/ast/control/ConditionalExpr.expected
@@ -18,6 +18,8 @@ conditionalExprs
 | conditionals.rb:55:1:55:18 | ... unless ... | UnlessModifierExpr | conditionals.rb:55:14:55:18 | ... < ... | conditionals.rb:55:1:55:5 | ... = ... | false |
 | conditionals.rb:58:5:58:25 | ... ? ... : ... | TernaryIfExpr | conditionals.rb:58:5:58:9 | ... > ... | conditionals.rb:58:13:58:17 | ... + ... | true |
 | conditionals.rb:58:5:58:25 | ... ? ... : ... | TernaryIfExpr | conditionals.rb:58:5:58:9 | ... > ... | conditionals.rb:58:21:58:25 | ... - ... | false |
+| conditionals.rb:61:1:64:3 | if ... | IfExpr | conditionals.rb:61:4:61:8 | ... > ... | conditionals.rb:61:10:62:5 | c | true |
+| conditionals.rb:67:1:70:3 | if ... | IfExpr | conditionals.rb:67:4:67:8 | ... > ... | conditionals.rb:68:1:69:5 | c | false |
 ifExprs
 | conditionals.rb:10:1:12:3 | if ... | IfExpr | conditionals.rb:10:4:10:8 | ... > ... | conditionals.rb:10:10:11:5 | c | (none) | false |
 | conditionals.rb:15:1:19:3 | if ... | IfExpr | conditionals.rb:15:4:15:9 | ... == ... | conditionals.rb:15:10:16:5 | c | d | false |
@@ -26,6 +28,7 @@ ifExprs
 | conditionals.rb:26:1:29:5 | elsif ... | IfExpr | conditionals.rb:26:7:26:12 | ... == ... | conditionals.rb:26:14:27:5 | e | f | true |
 | conditionals.rb:33:1:37:3 | if ... | IfExpr | conditionals.rb:33:4:33:9 | ... == ... | conditionals.rb:33:10:34:5 | b | elsif ... | false |
 | conditionals.rb:35:1:36:5 | elsif ... | IfExpr | conditionals.rb:35:7:35:12 | ... == ... | conditionals.rb:35:13:36:5 | c | (none) | true |
+| conditionals.rb:61:1:64:3 | if ... | IfExpr | conditionals.rb:61:4:61:8 | ... > ... | conditionals.rb:61:10:62:5 | c | (none) | false |
 unlessExprs
 | conditionals.rb:40:1:42:3 | unless ... | UnlessExpr | conditionals.rb:40:8:40:12 | ... > ... | conditionals.rb:40:14:41:5 | c | (none) |
 | conditionals.rb:45:1:49:3 | unless ... | UnlessExpr | conditionals.rb:45:8:45:13 | ... == ... | conditionals.rb:45:14:46:5 | c | d |
diff --git a/ql/test/library-tests/ast/control/ControlExpr.expected b/ql/test/library-tests/ast/control/ControlExpr.expected
index 3273ce0c6a4..9088fd6ed14 100644
--- a/ql/test/library-tests/ast/control/ControlExpr.expected
+++ b/ql/test/library-tests/ast/control/ControlExpr.expected
@@ -12,6 +12,8 @@
 | conditionals.rb:52:1:52:14 | ... if ... | IfModifierExpr |
 | conditionals.rb:55:1:55:18 | ... unless ... | UnlessModifierExpr |
 | conditionals.rb:58:5:58:25 | ... ? ... : ... | TernaryIfExpr |
+| conditionals.rb:61:1:64:3 | if ... | IfExpr |
+| conditionals.rb:67:1:70:3 | if ... | IfExpr |
 | loops.rb:9:1:12:3 | for ... in ... | ForExpr |
 | loops.rb:16:1:19:3 | for ... in ... | ForExpr |
 | loops.rb:22:1:25:3 | for ... in ... | ForExpr |
@@ -22,3 +24,4 @@
 | loops.rb:51:1:54:3 | until ... | UntilExpr |
 | loops.rb:57:1:60:3 | until ... | UntilExpr |
 | loops.rb:63:1:63:19 | ... until ... | UntilModifierExpr |
+| loops.rb:66:1:67:3 | while ... | WhileExpr |
diff --git a/ql/test/library-tests/ast/control/conditionals.rb b/ql/test/library-tests/ast/control/conditionals.rb
index 946a2d6659f..85e008f5c1d 100644
--- a/ql/test/library-tests/ast/control/conditionals.rb
+++ b/ql/test/library-tests/ast/control/conditionals.rb
@@ -55,4 +55,16 @@ a = b if c > d
 a = b unless c < d
 
 # Ternary if expr
-a = b > c ? d + 1 : e - 2
\ No newline at end of file
+a = b > c ? d + 1 : e - 2
+
+# If expr with empty else (treated as no else)
+if a > b then
+    c
+else
+end
+
+# If expr with empty then (treated as no then)
+if a > b then
+else
+    c
+end
\ No newline at end of file
diff --git a/ql/test/library-tests/ast/control/loops.rb b/ql/test/library-tests/ast/control/loops.rb
index e6bead6c401..b00a61e348b 100644
--- a/ql/test/library-tests/ast/control/loops.rb
+++ b/ql/test/library-tests/ast/control/loops.rb
@@ -60,4 +60,8 @@ until x > y do
 end
 
 # Until-modified expression
-x -= 1 until x == 0
\ No newline at end of file
+x -= 1 until x == 0
+
+# While loop with empty `do` block
+while x < y do
+end
diff --git a/ql/test/library-tests/controlflow/graph/Cfg.expected b/ql/test/library-tests/controlflow/graph/Cfg.expected
index b585b8ac4f0..52883ed1797 100644
--- a/ql/test/library-tests/controlflow/graph/Cfg.expected
+++ b/ql/test/library-tests/controlflow/graph/Cfg.expected
@@ -2330,7 +2330,7 @@ ifs.rb:
 #-----|  -> true
 
 #   40| constant_condition
-#-----|  -> exit ifs.rb (normal)
+#-----|  -> empty_else
 
 #   40| exit constant_condition
 
@@ -2346,6 +2346,39 @@ ifs.rb:
 #   41| true
 #-----| true -> [false] ! ...
 
+#   46| enter empty_else
+#-----|  -> b
+
+#   46| empty_else
+#-----|  -> exit ifs.rb (normal)
+
+#   46| exit empty_else
+
+#   46| exit empty_else (normal)
+#-----|  -> exit empty_else
+
+#   46| b
+#-----|  -> b
+
+#   47| if ...
+#-----|  -> "done"
+
+#   47| b
+#-----| true -> "true"
+#-----| false -> if ...
+
+#   48| call to puts
+#-----|  -> if ...
+
+#   48| "true"
+#-----|  -> call to puts
+
+#   51| call to puts
+#-----|  -> exit empty_else (normal)
+
+#   51| "done"
+#-----|  -> call to puts
+
 loops.rb:
 #    1| enter m1
 #-----|  -> x
@@ -2503,7 +2536,7 @@ loops.rb:
 #-----|  -> 1
 
 #   24| m3
-#-----|  -> exit loops.rb (normal)
+#-----|  -> m4
 
 #   24| exit m3
 
@@ -2545,6 +2578,36 @@ loops.rb:
 #   26| x
 #-----|  -> call to puts
 
+#   30| enter m4
+#-----|  -> x
+
+#   30| m4
+#-----|  -> exit loops.rb (normal)
+
+#   30| exit m4
+
+#   30| exit m4 (normal)
+#-----|  -> exit m4
+
+#   30| x
+#-----|  -> y
+
+#   30| y
+#-----|  -> x
+
+#   31| while ...
+#-----|  -> exit m4 (normal)
+
+#   31| ... < ...
+#-----| true -> x
+#-----| false -> while ...
+
+#   31| x
+#-----|  -> y
+
+#   31| y
+#-----|  -> ... < ...
+
 raise.rb:
 #    1| enter raise.rb
 #-----|  -> ExceptionA
diff --git a/ql/test/library-tests/controlflow/graph/ifs.rb b/ql/test/library-tests/controlflow/graph/ifs.rb
index aa8ac8a342b..30a3f169a5d 100644
--- a/ql/test/library-tests/controlflow/graph/ifs.rb
+++ b/ql/test/library-tests/controlflow/graph/ifs.rb
@@ -42,3 +42,11 @@ def constant_condition()
     puts "Impossible"
   end
 end
+
+def empty_else b
+  if b then
+    puts "true"
+  else
+  end
+  puts "done"
+end
\ No newline at end of file
diff --git a/ql/test/library-tests/controlflow/graph/loops.rb b/ql/test/library-tests/controlflow/graph/loops.rb
index 01222db77e1..b3f1c60557a 100644
--- a/ql/test/library-tests/controlflow/graph/loops.rb
+++ b/ql/test/library-tests/controlflow/graph/loops.rb
@@ -25,4 +25,9 @@ def m3
   [1,2,3].each do |x|
     puts x
   end
-end
\ No newline at end of file
+end
+
+def m4(x, y)
+  while x < y do
+  end
+end