diff --git a/crates/sema/src/ast_passes.rs b/crates/sema/src/ast_passes.rs
index 6b1c1b27..64ea0813 100644
--- a/crates/sema/src/ast_passes.rs
+++ b/crates/sema/src/ast_passes.rs
@@ -50,6 +50,16 @@ impl<'sess> AstValidator<'sess, '_> {
     fn in_loop(&self) -> bool {
         self.in_loop_depth != 0
     }
+
+    fn check_single_statement_variable_declaration(&self, stmt: &ast::Stmt<'_>) {
+        if matches!(stmt.kind, ast::StmtKind::DeclSingle(..) | ast::StmtKind::DeclMulti(..)) {
+            self.dcx()
+                .err("variable declarations can only be used inside blocks")
+                .span(stmt.span)
+                .help("wrap the statement in a block (`{ ... }`)")
+                .emit();
+        }
+    }
 }
 
 impl<'ast> Visit<'ast> for AstValidator<'_, 'ast> {
@@ -121,14 +131,21 @@ impl<'ast> Visit<'ast> for AstValidator<'_, 'ast> {
 
     fn visit_stmt(&mut self, stmt: &'ast ast::Stmt<'ast>) -> ControlFlow<Self::BreakValue> {
         match &stmt.kind {
-            ast::StmtKind::While(_, body, ..)
-            | ast::StmtKind::DoWhile(body, ..)
+            ast::StmtKind::While(_, body)
+            | ast::StmtKind::DoWhile(body, _)
             | ast::StmtKind::For { body, .. } => {
                 self.in_loop_depth += 1;
-                let r = self.walk_stmt(body);
+                self.check_single_statement_variable_declaration(body);
+                let r = self.walk_stmt(stmt);
                 self.in_loop_depth -= 1;
                 return r;
             }
+            ast::StmtKind::If(_cond, then, else_) => {
+                self.check_single_statement_variable_declaration(then);
+                if let Some(else_) = else_ {
+                    self.check_single_statement_variable_declaration(else_);
+                }
+            }
             ast::StmtKind::Break | ast::StmtKind::Continue => {
                 if !self.in_loop() {
                     let kind = if matches!(stmt.kind, ast::StmtKind::Break) {
@@ -140,14 +157,14 @@ impl<'ast> Visit<'ast> for AstValidator<'_, 'ast> {
                     self.dcx().err(msg).span(stmt.span).emit();
                 }
             }
-            ast::StmtKind::UncheckedBlock(block) => {
+            ast::StmtKind::UncheckedBlock(_block) => {
                 if self.in_unchecked_block {
                     self.dcx().err("`unchecked` blocks cannot be nested").span(stmt.span).emit();
                 }
 
                 let prev = self.in_unchecked_block;
                 self.in_unchecked_block = true;
-                let r = self.walk_block(block);
+                let r = self.walk_stmt(stmt);
                 self.in_unchecked_block = prev;
                 return r;
             }
diff --git a/tests/ui/resolve/loops.sol b/tests/ui/resolve/loops.sol
index e164168a..1b67b884 100644
--- a/tests/ui/resolve/loops.sol
+++ b/tests/ui/resolve/loops.sol
@@ -10,20 +10,17 @@ function funky() {
     for (; i < 40; i++) continue;
     for (; i++ < 50;) continue;
 
-    // ---
-    // TODO: `Error: Variable declarations can only be used inside blocks.`
-
-    while (a == 0) uint a = 0; //~ ERROR: unresolved symbol
+    while (a == 0) { uint a = 0; } //~ ERROR: unresolved symbol 
     a; //~ ERROR: unresolved symbol
     while (b == 0) { uint b = 0; } //~ ERROR: unresolved symbol
     b; //~ ERROR: unresolved symbol
 
-    do uint c; while (c == 0); //~ ERROR: unresolved symbol
+    do { uint c; } while (c == 0); //~ ERROR: unresolved symbol
     c; //~ ERROR: unresolved symbol
     do { uint d; } while (d == 0); //~ ERROR: unresolved symbol
     d; //~ ERROR: unresolved symbol
 
-    for (; false; e++) uint e; //~ ERROR: unresolved symbol
+    for (; false; e++) { uint e; } //~ ERROR: unresolved symbol
     e; //~ ERROR: unresolved symbol
     for (; false; f++) { uint f; } //~ ERROR: unresolved symbol
     f; //~ ERROR: unresolved symbol
@@ -32,3 +29,4 @@ function funky() {
     }
     g; //~ ERROR: unresolved symbol
 }
+
diff --git a/tests/ui/resolve/loops.stderr b/tests/ui/resolve/loops.stderr
index de63bf92..c231a54f 100644
--- a/tests/ui/resolve/loops.stderr
+++ b/tests/ui/resolve/loops.stderr
@@ -1,7 +1,7 @@
 error: unresolved symbol `a`
   --> ROOT/tests/ui/resolve/loops.sol:LL:CC
    |
-LL |     while (a == 0) uint a = 0;
+LL |     while (a == 0) { uint a = 0; }
    |            ^
    |
 
@@ -29,8 +29,8 @@ LL |     b;
 error: unresolved symbol `c`
   --> ROOT/tests/ui/resolve/loops.sol:LL:CC
    |
-LL |     do uint c; while (c == 0);
-   |                       ^
+LL |     do { uint c; } while (c == 0);
+   |                           ^
    |
 
 error: unresolved symbol `c`
@@ -57,7 +57,7 @@ LL |     d;
 error: unresolved symbol `e`
   --> ROOT/tests/ui/resolve/loops.sol:LL:CC
    |
-LL |     for (; false; e++) uint e;
+LL |     for (; false; e++) { uint e; }
    |                   ^
    |
 
diff --git a/tests/ui/typeck/var_decl_as_loop_body.sol b/tests/ui/typeck/var_decl_as_loop_body.sol
new file mode 100644
index 00000000..0e2f5fe5
--- /dev/null
+++ b/tests/ui/typeck/var_decl_as_loop_body.sol
@@ -0,0 +1,28 @@
+contract C {
+    function var_decl_inside_loops() external {
+        for (uint256 i = 0; i < 100; ++i) {
+            uint256 m_count = i + 1 * 2;
+        }
+
+        for (uint256 i = 0; i < 100; ++i) uint256 m_count = i + 1 * 2; //~ ERROR: variable declarations can only be used inside blocks
+        for (uint256 i = 0; i < 100; ++i)
+            for (uint256 j = 0; i < 100; ++j) {
+                uint256 k = i + j;
+            }
+
+        for (uint256 i = 0; i < 100; ++i)
+            for (uint256 j = 0; i < 100; ++j) uint256 k = i + j; //~ ERROR: variable declarations can only be used inside blocks
+
+        while (true) uint256 x = 4; //~ ERROR: variable declarations can only be used inside blocks
+
+        do uint256 x = 4; while (true); //~ ERROR: variable declarations can only be used inside blocks
+
+        unchecked {
+            {
+                {
+                    for (uint256 i = 0; i < 10; ++i) uint256 y = 0; //~ ERROR: variable declarations can only be used inside blocks          
+                }
+            }
+        }
+    }
+}
diff --git a/tests/ui/typeck/var_decl_as_loop_body.stderr b/tests/ui/typeck/var_decl_as_loop_body.stderr
new file mode 100644
index 00000000..5a06a978
--- /dev/null
+++ b/tests/ui/typeck/var_decl_as_loop_body.stderr
@@ -0,0 +1,42 @@
+error: variable declarations can only be used inside blocks
+  --> ROOT/tests/ui/typeck/var_decl_as_loop_body.sol:LL:CC
+   |
+LL |         for (uint256 i = 0; i < 100; ++i) uint256 m_count = i + 1 * 2;
+   |                                           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = help: wrap the statement in a block (`{ ... }`)
+
+error: variable declarations can only be used inside blocks
+  --> ROOT/tests/ui/typeck/var_decl_as_loop_body.sol:LL:CC
+   |
+LL |             for (uint256 j = 0; i < 100; ++j) uint256 k = i + j;
+   |                                               ^^^^^^^^^^^^^^^^^^
+   |
+   = help: wrap the statement in a block (`{ ... }`)
+
+error: variable declarations can only be used inside blocks
+  --> ROOT/tests/ui/typeck/var_decl_as_loop_body.sol:LL:CC
+   |
+LL |         while (true) uint256 x = 4;
+   |                      ^^^^^^^^^^^^^^
+   |
+   = help: wrap the statement in a block (`{ ... }`)
+
+error: variable declarations can only be used inside blocks
+  --> ROOT/tests/ui/typeck/var_decl_as_loop_body.sol:LL:CC
+   |
+LL |         do uint256 x = 4; while (true);
+   |            ^^^^^^^^^^^^^^
+   |
+   = help: wrap the statement in a block (`{ ... }`)
+
+error: variable declarations can only be used inside blocks
+  --> ROOT/tests/ui/typeck/var_decl_as_loop_body.sol:LL:CC
+   |
+LL | ...   for (uint256 i = 0; i < 10; ++i) uint256 y = 0;
+   |                                        ^^^^^^^^^^^^^^
+   |
+   = help: wrap the statement in a block (`{ ... }`)
+
+error: aborting due to 5 previous errors
+